Hybrid proteins with modified activity

ABSTRACT

Hybrid proteins which affect blood coagulation comprise a region from a donor anticoagulant or antithrombotic protein, and the resulting hybrid protein has a modified biological activity. Information concerning the hybrid proteins implicates DNA sequences encoding the proteins and hosts, including transgenic animals, that possess these DNA sequences; antibodies directed against hybrid proteins; methods of modifying the properties of proteins; and treatment methods employing hybrid proteins.

This application is a division of application Ser. No. 08/558,107, filed Nov. 13, 1995.

The present invention relates to hybrid blood coagulation proteins with modified activities, such as enhanced coagulation activities. The hybrid proteins according to the invention can be obtained by replacing at least one region of a blood coagulation protein with at least one region from a donor anticoagulant or antithrombotic protein.

BACKGROUND OF THE INVENTION

Hybrid proteins have been described previously. For example, many hybrid proteins have been constructed to combine the functions of two proteins into one, such as an interleukin fused to a toxin. Kreitman et al., Biochemistry 33: 11637-44 (1994); Foss et al., Blood 84: 1765-74 (1994). In other cases, proteins have been fused to portions of other proteins that have a specific biological function. For instance, propeptides of hemostatic proteins (WO 88/03926) or stabilizing portions of albumin (WO 89/02922) have been employed in this manner.

The substitutions of various domains by domains derived from other proteins have been described for protein C (U.S. Pat. No. 5,358,932; EP 296 413), angiogenin (U.S. Pat. No. 5,286,487), fibroblast growth factor (JP-J03184998), α-interferon (EP 146 903), tissue plasminogen activator (WO 88/08451, EP 352 119) Factor V (U.S. Pat. No. 5,004,803) and Factor VIII. However, the exchange of regions between blood proteins with antagonistic functions has never been described before.

Blood proteins, which include procoagulant proteins, anticoagulant proteins and antithrombotic proteins, are among the proteins whose in vitro expression has been of great interest ever since the isolation of their corresponding genes and cDNAs. Procoagulant proteins cause coagulation to occur. In contrast, anticoagulant proteins inhibit the formation of fibrin clots, and antithrombotic proteins inhibit the formation of thrombi, which usually are larger than fibrin clots and comprise fibrin, platelets and adhesion proteins.

Blood coagulation involves a series of proteolytic events that ultimately result in the formation of an insoluble fibrin clot. The scheme of blood coagulation has been described as a cascade or "water fall," and depends on the activation properties of various serine proteases. Davie et al., Science 145: 1310-12 (1964); MacFarlane, Nature 202: 498-99 (1964). In blood, all the serine proteases involved in blood coagulation are present as inactive precursor proteins, which are activated upon proteolytic cleavage by the appropriate activator. Blood coagulation further involves non-enzymatic cofactors that control the properties of the various blood proteins. For example, Factor V and Factor VIII function as non-enzymatic cofactors for Factor Xa and Factor IXa in the intrinsic pathway of blood coagulation. See Mann et al., Blood 76: 1-16 (1990). Activated Factor VIIIa functions in the middle of the intrinsic coagulation cascade, acting as a cofactor for Factor X activation by Factor IXa in the presence of calcium ions and phospholipids. See Jackson, et al., Ann. Rev. Biochem. 49: 765 (1980).

The natural antagonist of the blood coagulation system is the anticoagulant system. In the plasma of a healthy mammalian organism, the actions of both systems are well balanced. In case of vessel injury, blood coagulation involves the deposition of a matrix of fibrin at the damaged site. After repair of the damage, the matrix of fibrin is removed by fibrinolysis.

In the anticoagulant system, a number of pathways operate to limit the extent of clot formation. Several serine protease inhibitors, such as antithrombin and heparin cofactor II, specifically interact with the activated serine proteases of the blood coagulation cascade. Additional control is provided by the protein C anticoagulant pathway, which results in the inactivation of the non-enzymatic cofactors Factor V and Factor VIII. Defects in the anticoagulant pathways are commonly associated with venous thrombosis.

Permanent and temporary disorders in blood coagulation and fibrinolysis require the administration of specific factors of the respective system. Thrombotic complications require the administration of anticoagulant proteins that are derived from the mammalian anticoagulant system, for example Protein C or Protein S.

The administration of Factor VIII, Factor IX or other blood coagulation factors is required during temporary (that is, non-genetic) blood coagulation disorders. Surgery is one type of temporary blood disorder. The various forms of hemophilia, which include genetic disorders that effect blood coagulation, also require the administration of specific coagulation factors, such as Factor VIII or Factor IX.

The functional absence of one of the procoagulant proteins involved in blood coagulation is usually associated with a bleeding tendency. The most common bleeding disorder in man is hemophilia A, an X-chromosome-linked bleeding disorder which affects about 0.01% of the male population. Hemophilia A is associated with the functional absence of Factor VIII. Hemophilia A is conventionally treated by the administration of purified Factor VIII preparations isolated from plasma of healthy donors. The treatment has several disadvantages. The supply of Factor VIII from plasma donors is limited and very expensive; the concentration of Factor VIII in blood is only about 100 ng/ml and the yields using common plasma fractionation methods are low. Additionally, although preparation methods of blood factors from human plasma have improved with regard to virus-safety, there still remains an element of risk concerning the transmission of infectious agents, including hepatitis viruses and HIV.

The isolation of a functional Factor VIII cDNA has led to the production of recombinant Factor VIII in cultured cells. Molecular cloning of Factor VIII cDNA obtained from human mRNA and the subsequent production of proteins with Factor VIII activity in mammalian, yeast and bacterial cells has been reported. See WO 85/01961; EP 160 457; EP 150 735; EP 253 455. Recombinant production has led to improvements with regard to product purity and virus safety. Factor VIII stability was not improved, however, and supply of Factor VIII from in vitro production also is limited due to low yields. Accordingly, therapy costs remain high because Factor VIII must be administered frequently.

The short in vivo half-life of wild-type Factor VIII is one reason for the frequent administration of wild-type Factor VIII in the treatment of hemophilia A. As a consequence, recipients sometimes develop antibodies against the exogenous Factor VIII that is administered, which can greatly reduce its effectiveness leading to the necessity to further increase the dose given.

For example, between 11% and 13% of the hemophilia A patients treated with Factor VIII products develop antibodies against Factor VIII. See Aledort, Sem. Hematol. 30: 7-9 (1993). In an attempt to induce immunotolerance, hemophilia A patients with antibodies against Factor VIII are treated with high doses of Factor VIII. Brackman et al., Lancet 2: 933 (1977). But high dosage administration is very expensive.

The problems-associated with factor VIII administration in the prior art may be circumvented, however, if the concentration of protein administered to obtain a Factor VIII activity in the blood of hemophiliacs can be kept sufficiently low to escape immunodetection and production of anti-Factor VIII antibodies while still obtaining the needed positive effects of Factor VIII. Accordingly, there is need for Factor VIII derivatives with improved functional properties, so that more units of Factor VIII activity can be delivered per molecule administered, thus allowing reduction in dosage and frequency of administration.

Factor VIII has three acidic regions which contain sulfated tyrosines adjacent to cleavage sites for thrombin at the regions from Met³³⁷ to Arg³⁷² and from Ser⁷¹⁰ to Arg⁷⁴⁰ in the heavy chain and from Glu¹⁶⁴⁹ to Arg¹⁶⁸⁹ in the light chain. See Mikkelsen et al., Biochemistry 30: 1533-37 (1991); Pittman et al., loc. cit. 31: 3315-25 (1992); Eaton et al., Biochemistry 25: 8343-47 (1986). In all three cases, the acidic regions contain one or more tyrosine residues which have been shown to be sulfated. Sulfation of Tyr¹⁶⁸⁰ is essential for the interaction of Factor VIII with von Willebrand Factor. See Leyte et al., J. Biol. Chem. 266: 740-46 (1991). While the role of the sulfated Tyr³⁴⁶ is not known, Fay et al. Thromb. Haemost. 70: 63-67 (1993), such that it is likely to be involved in the interaction between the A1 and A2 domains in activated Factor VIII. Sulfation of Tyr⁷¹⁸, Tyr⁷¹⁹ and Tyr⁷²³ was shown to increase the intrinsic activity of activated Factor VIIIa. Michnick et al., J. Biol. Chem. 269: 20095-102 (1994). Functional analysis of Factor VIII-del(713-1637), a deletion mutant of Factor VIII lacking most of the B-domain and the acidic region that contains Tyr⁷¹⁸, Tyr⁷¹⁹ and Tyr⁷²³, showed that it was defective in procoagulant activity. Biochemical analysis revealed that full activation of Factor VIII-del(713-1637) required elevated amounts of thrombin compared to the wild-type molecule. Mertens et al., Brit. J. Haematol. 85: 133-42 (1993).

Thrombin is the enzyme responsible for the activation of Factor VIII. Thrombin, moreover, plays many other roles in the coagulation cascade. Proteolytic cleavage of fibrinogen by thrombin produces the fibrin monomer, which then polymerizes to form the insoluble fibrin clot. Furthermore, thrombin can initiate a number of positive and negative feedback loops that either sustain or downregulate clot formation. Stubbs et al., Thromb. Res. 69: 1-58 (1993); Davie et al., Biochem. 30: 10363-70 (1991). Binding of thrombin to its platelet receptor is associated with stimulation and aggregation of platelets (Coughlin et al., J. Clin. Invest. 89:351-55 (1992). Limited proteolysis by thrombin activates the non-enzymatic cofactors V and VIII, which enhances Factor X and prothrombin activation. Kane et al. Blood 71: 539-55 (1988). Additionally, there is evidence that thrombin is involved in the activation of Factor XI. Gailani et al., Science 253: 909-12 (1991). When bound to the endothelial cell receptor thrombomodulin, thrombin works as an anticoagulant by activating protein C. Esmon, Thromb. Haemost. 70: 29-35 (1993). In the presence of glycosaminoglycans, thrombin is specifically inhibited by the serine protease inhibitors, anti-thrombin and heparin cofactor II. Huber et al., Biochem. 28: 8952-66 (1989).

Determination of the three-dimensional structure of the complexes that thrombin forms with the synthetic inhibitor PPACK, as well as with hirudin, an anticoagulant protein originally isolated from leeches, have defined an important role for a positively charged area, known as the "anion exosite," in the interaction of thrombin with other proteins. Bode et al., EMBO J. 11: 3467-75 (1989); Skrzypczak-Jankun et al., J. Mol. Biol. 206: 755-57 (1989); Rydel et al., Science 249: 277-80 91990); Grutter et al., EMBO J. 9: 2361-65 (1990). The best described three-dimensional structure is that of the thrombin-hirudin complex, where the acidic region in the carboxy-terminal region of hirudin is in close contact with the anion exosite of thrombin. Grutter et al., EMBO J 9: 2361-65 (1990); Rydel et al., Science 249: 277-80 (1990). Stretches of negatively charged amino acids of the thrombin receptor, thrombomodulin and heparin cofactor II, which are similar to those in hirudin, have been shown to interact with the anion exosite of thrombin. Liu et al., J. Biol. Chem. 266: 16977-80 (1991); Vu et al., Nature 353: 674-77 (1991); Mathews et al., Biochemistry 33: 3266-79 (1994); Tsiang et al., Biochemistry 29: 10602-12 (1990); Van Deerlin et al., J. Biol. Chem. 266: 20223-31 (1990). Studies which employ synthetic peptides corresponding to the negatively charged areas of these proteins have shown that they have different affinities for thrombin. These studies indicate that the degree of affinity of thrombin for other proteins depends in part on the acidic regions of those other proteins. Tsiang et al., Biochem. 29: 10602-12 (1990); Hortin et al., Biochem. Biophys. Res. Commun. 169: 437-442 (1990).

In the activated state, Factor VIII is a heterotrimer comprising the amino acid residues 1-372 (containing the A1 domain) and 373-740 (containing the A2 domain) of the heavy chain and residues 1690-2332 (the domains A3-C1-C2) of the light chain. See Eaton et al., Biochem. 25: 505-12 (1986), and Lollar et al. Biochemistry 28: 666-74 (1989). In comparison with the inactive Factor VIII precursor, the active Factor VIII thus lacks the light chain fragment 1649-1689, which is involved in the interaction of Factor VIII with von Willebrand factor, Lollar et al., J. Biol. Chem. 263: 10451-55 (1988), as well as the complete B-domain region 741-1648.

The finding that the complete B-domain is proteolytically removed when Factor VIII is activated has led to the construction of various B-domain deletion mutants. Such Factor VIII B-domain deletion mutants were found to result in increased production levels of recombinant Factor VIII. See EP 294 910; WO 86/06101; U.S. Pat. No. 4,868,112; Toole et al., Proc. Nat'l Acad. Sci. USA 83: 5939-42 (1986); Eaton et al. Biochemistry 25: 8343-47 (1986); Sarver et al., DNA 6:553-64 (1987). The deletion mutant Factor VIIIdel(868-1562), which is denoted "Factor VIII dB695" here, has been shown to be similar to plasma Factor VIII with regard to binding to von Willebrand Factor, half-life and recovery of Factor VIII dB695 upon infusion into dogs with hemophilia A. Mertens et al., Brit. J. Haematol. 85:133-142 (1993).

Other hybrid molecules with Factor VIII activity have been described. In U.S. Pat. No. 5,004,803, for example, a Factor VIII molecule is described that retains Factor VIII activity when a Factor V B-domain is substituted for the natural B-domain. International application WO 94/11013 discloses chimeric Factor VIII in which one or more exons are substituted by the corresponding exons of Factor V and chimeric Factor V in which one or more exons are substituted by the corresponding exons of Factor VIII.

U.S. Pat. No. 5,364,771 describes human/porcine Factor VIII hybrids. These hybrids are obtained by mixing porcine Factor VIII heavy chain with human Factor VIII light chain and vice versa, or via recombinant DNA technology. A recombinant molecule with Factor VIII activity is described where the A2-domain of porcine Factor VIII has been substituted for the A2-domain of human Factor VIII. WO 94/11503 describes various constructs wherein domains of porcine Factor VIII are substituted for corresponding regions in human Factor VIII. Some of these porcine/human factor VIII hybrids exhibit increased Factor VIII activity when compared to wild-type Factor VIII, as determined by the Kabi Coatest Chromogenic Assay. The maximum increase of 3.8-fold, however, is only achieved when the large domain between amino acid positions 336 and 740 in human Factor VIII is replaced by its porcine counterpart. This domain represents the structurally but not biochemically defined unit, which is the A2-domain plus some additional amino acid residues on either side.

International applications WO 95/18827 and WO 95/18829 disclose Factor VIII derivatives wherein single amino acids in the A2 domain have been deleted or substituted to give a more stable protein with Factor VIII activity. In the latter application, only single amino acids are deleted or substituted. The procoagulant activity of all of these Factor VIII derivatives is not different from that of wild-type Factor VIII, however.

International application WO 95/18828 describes Factor VIII derivatives wherein single amino acids in the A2 domain have been deleted or substituted to give a protein with the same activity as wild-type Factor VIII, but which is reportedly capable of being prepared in greater yield by recombinant DNA techniques.

With regard to other proteins, international application WO 91/05048 discloses mutants of human plasminogen activator inhibitor whose reactive centers are replaced by the reactive center of antithrombin III. As a result, the mutants can exhibit different properties, such as reactivity with serine proteases. But this publication does not involve blood coagulation proteins, nor does it discuss the insertion of acidic regions. European application 296 413 describes a hybrid protein C whose Gla domain is replaced by another Gla domain derived from another vitamin K-dependent protein.

SUMMARY OF THE INVENTION

It therefore is an object of the present invention to provide hybrid proteins derived from blood coagulation proteins and having modified characteristics, as well as methods of making such proteins and treating patients with the hybrid proteins.

It is another object of the present invention to provide hybrid proteins that have modified characteristics by replacing at least one region in a blood coagulation protein by a region(s) from a donor protein, the donor protein being an anticoagulant or an antithrombotic protein.

It is yet another object of the present invention to provide improved hybrid proteins that have the therapeutic properties of Factor VIII.

In accomplishing these and other objects, there is provided a hybrid protein derived from a blood coagulation protein, wherein the hybrid protein comprises a region or regions from a donor anticoagulant or antithrombotic protein or from a wholly or partially synthetic polypeptide, whereby the hybrid protein has a modified biological activity.

A hybrid protein preferably is derived from a blood coagulation protein selected from the group consisting of Factor V, Factor VIII, Factor X, Factor XIII, fibrinogen, protein S and protein C. It also is preferable that the region inserted into the hybrid protein has an affinity for a serine protease, such as thrombin. This region(s) can have a greater or lesser affinity for the serine protease than native region(s) of the blood coagulation protein. Preferably, the region is an acidic region, and comprises a binding site for a serine protease. In a preferred embodiment, the region is from a protein selected from the group consisting of heparin cofactor II, antithrombin III and hirudin.

In accordance with another aspect of the present invention, there are provided hybrid proteins that comprise a first region of a blood coagulation protein and a second region of an anticoagulant or antithrombotic protein wherein (A) the second region has an affinity for a serine protease and (B) the hybrid protein has a biological activity that is characteristic of the blood coagulation protein but which is modified in the hybrid protein. The blood coagulation protein can be Factor V, Factor VIII, Factor X, Factor XIII, fibrinogen, protein S and protein C. The anticoagulant or antithrombotic protein can be antithrombin III, heparin cofactor II and hirudin. Preferably, the region from the anticoagulant or antithrombotic protein is an acidic region, and comprises a binding site for a serine protease, such as thrombin.

In accordance with still another aspect of the present invention, the blood coagulation protein is Factor VIII or a Factor VIII mutant that lacks a portion of the B-domain, such as Factor VIII db695 or Factor VIII db928. Preferably, at least one of the Factor VIII or Factor VIII mutant acidic regions located between amino acid residues 336 and 372, amino acid residues 705 and 740, preferably 712 to 737 or 718 to 732, and amino acid residues 1648 and 1689 are replaced by amino acids 53 to 62 of hirudin or amino acids 45 to 90, preferably 51 to 81, of heparin cofactor II. Additionally, the Factor VIII or Factor VIII mutant can have two or more acidic regions and/or regions having an affinity for a serine protease replaced.

In accordance with still another aspect of the present invention, there are provided pharmaceutical compositions containing hybrid proteins, polynucleotides (including vectors) encoding hybrid proteins, transformed cells containing these polynucleotides, and antibodies directed against hybrid proteins. Methods of modifying the biological activities of proteins also are provided.

These and other aspects of the present invention will become apparent to the skilled artisan in view of the disclosure contained herein. Modifications may be made to the various teachings of this invention without departing from the scope and spirit of the invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of Factor VIII and Heparin cofactor II. The domains of Factor VIII (A1-A2-B-A3-C1-C2) are interspersed by acidic regions at amino acid positions Met³⁷³ -Arg³⁷², Ser⁷¹⁰ -Arg⁷⁴⁰ and Glu¹⁶⁴⁹ -Arg¹⁶⁸⁹ of human Factor VIII. Cleavage sites for thrombin are indicated by arrows. Similarly, an acidic region of heparin cofactor II, an inhibitor of thrombin, is located between amino acid residues 51 and 81. The reactive site of heparin cofactor II, Leu⁴⁴⁴ -Ser⁴⁴⁵, is indicated by a vertical line (LS). In the lower section of the schematic representation, the amino acid sequences of the region from Val⁷⁰⁸ -Ser⁷⁴⁶ of human Factor VIII and the corresponding region of Factor VIII dB695-HCII is set forth. Beneath the schematic representations, the upper amino acid sequence shows the region from Val⁷⁰⁸ -Ser⁷⁴⁶ of human Factor VIII (FVIII), which contains an acidic region (Ser⁷¹⁰ -Arg⁷⁴⁰) and a cleavage site for thrombin at position Arg⁴⁷⁰. The three sulfated tyrosines at amino acid positions 718, 719 and 723 are indicated by asterisks. The lower sequence shows the corresponding region of Factor VIII dB695-HCII FVIII-HCII). Amino acid residues derived from the A2-domain of human Factor VIII are underlined. Sulfated tyrosine residues are indicated by asterisks (SEQ ID NOS: 15 and 16).

FIG. 2 is a schematic diagram of plasmid pCLB-dB695-HCII. The nucleotide sequence encoding Factor VIII dB695-HCII was inserted into plasmid pBPV (Pharmacia LKB, Sweden) and placed under the control of the metallothionein promoter (MT) and the mouse sarcoma virus (MSV) enhancer. The polyadenylation signal (poly A) is derived from SV40 and the β-lactamase gene (amp) and the origin of replication (or) are derived from the plasmid pML2, a derivative of pBR322. The presence of sequences derived from bovine papilloma virus (BPV) allows the extrachromosomal replication of the plasmid. Acidic regions derived from Factor VIII are indicated by hatched bars, the acidic region from Ile⁵¹ to Ser⁸¹ of human heparin cofactor II is indicated by a double-hatched bar. The deleted portion of the Factor VIII B-domain is indicated by an interrupted line.

FIG. 3 depicts the activation of Factor VIII dB695 by thrombin. Activation of acetylated Factor X was performed in the presence of 0.1 nM Factor IXa, 100 mM phospholipids and 0.2 nM Factor VIII in 100 mM NaCl, 10 mM CaCl₂, 50 mM Tris (pH 7.5) at 37° C. The reaction was initiated by the addition of different concentrations of thrombin: 0.1 nM (◯), 0.5 nM (), 1.0 nM (Δ) and 2.5 nM (▴). The amount of Factor Xa generated in time was monitored by subsampling into 50 μl of stop buffer and the addition of the chromogenic substrate Pefachrome Xa.

FIG. 4 depicts the activation of Factor VIII dB695-HCII by different concentrations of thrombin: 0.1 nM (◯); 0.2 nM () and 0.5 nM (Δ). The experiment was performed under the conditions as in FIG. 3.

FIG. 5 depicts the rate constants of thrombin activation of Factor VIII dB695 and Factor VIII dB695-HCII. Factor VIII activation was monitored at different concentrations of thrombin, as shown in FIGS. 3 and 4. For every thrombin concentration used, the first order rate constant of Factor VIII activation (k₁) was determined. From the slope of a plot of the first order rate constant k₁ against the concentration of thrombin, the second order rate constants of activation of Factor VIII dB695 and Factor VIII dB695-HCII were determined (see Table III). Data points correspond to Factor VIII dB695 (▪, ◯, +) and Factor VIII dB695-HCII (▴, ⋄). For Factor VIII dB695, the results of three different experiments are given. For Factor VIII dB695-HCII the results of two different experiment are displayed. At the x-axis the concentration of thrombin is depicted (1 nM); at the y-axis the first order rate constant of activation (k1) that is derived from equation 3 is given (M min⁻²).

FIG. 6 is a schematic representation of the hybrid Factor VIII dB695-HIR. The domains of Factor VIII (A1-A2-B-A3-C1-C2) are interspersed by acidic regions as described in FIG. 1. In the lower section of the figure, the amino acid sequence of the region Val⁷⁰⁸ -Ser⁷⁴⁶ of Factor VIII is depicted which contains an acidic region (Ser⁷¹⁰ -Arg⁷⁴⁰) and a cleavage site for thrombin at position Arg⁷⁴⁰. The sulfated tyrosines at amino acid position 718, 719 and 723 are indicated by asterisks. The sequence FVIII-HIR shows the corresponding region of the hybrid protein Factor VIII dB695-HIR. Amino acid sequences derived of the A2-domain of Factor VIII are underlined. The sulfated tyrosine obtained from the acidic region of hirudin is indicated by an asterisk (SEQ ID NOS: 15 and 17).

FIGS. 7A-7N depicts the nucleotide sequence (SEQ ID NO: 1) of a Factor VIII dB695-HCII cDNA as it is contained in vector pCLB-dB695-HCII, and the amino acid sequence (SEQ ID NO: 2) encoded by the cDNA (Factor VIII dB695-HCII). The translation initiation codon is located at nucleotide position 35 and the nucleotide sequence obtained from heparin cofactor II is located from nucleotide position 2225 to nucleotide position 2315. The protein encoded by this cDNA is 1661 amino acids long.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to hybrid proteins that can be derived from blood coagulation proteins, which are proteins having procoagulant properties. These hybrid proteins can be created by inserting at least one region from an anticoagulant or antithrombotic protein, or synthetic polypeptides, into a blood coagulation protein. These regions preferably have an affinity for a serine protease and, more preferably, are acidic regions.

The term "derived" in its various grammatical forms connotes a similarity that is indicative of an archetype. A hybrid protein derived from a blood coagulation protein would display an activity that is characteristic of the blood coagulation protein from which the hybrid protein is derived. In particular, the characteristic activity can include the ability of a protein to interact with other proteins to cause an effect. For example, a blood coagulation protein interacts with another protein in order to ultimately cause coagulation to occur.

Surprisingly, functional hybrid proteins have been obtained by combining a region(s) from a blood coagulation protein, which is a procoagulant protein, with a region(s) from an anticoagulant and/or antithrombotic protein, which are functional antagonists of procoagulant proteins. Thus, a key aspect of the present invention is the unexpected finding that proteins that are antagonistic of one another often contain regions that are not antagonistic, but rather perform the same or similar function in the given proteins.

The hybrid proteins according to the invention can be obtained by replacing one or more regions of a blood coagulation protein with one or more regions from a donor protein, such as anticoagulant and/or antithrombotic proteins, or with synthetic polypeptides having characteristics of an appropriate region. "Replacing" in its various grammatical forms relates to changing the sequence of a protein by substituting native amino acids with different amino acids. Preferably, the replaced region of the blood coagulation protein has an affinity for a serine protease, and the region(s) from the donor protein has greater or lesser affinity for serine proteases, depending upon the properties that are desired in the resulting hybrid protein.

A protein to be altered according to the invention is a blood coagulation protein or a polypeptide derived from such a protein. In a preferred embodiment of the present invention, the hybrid protein is based upon a naturally-occurring blood coagulation protein or other source polypeptide, such as mutants of naturally-occurring proteins and polypeptide sequences modeled upon rules developed through analyses of families of proteins, as well as the characteristics of individual amino acids.

As a consequence of the inclusion of the region from the anticoagulant or antithrombotic protein, one or more biological activities of the blood coagulation protein are modified in the resulting hybrid protein. The biological activities that may be modified include activation properties, enzymatic functions, immunogenic properties. Each of these activities depend upon the primary capability of the protein to interact with other proteins, such as co-factors, enzymes, receptors or antibodies. The modification may facilitate activation of the hybrid protein as compared to the native blood coagulant protein, often by causing the hybrid protein to have an increased affinity for the appropriate activator, such as a serine protease. The alteration also may modify the enzymatic activity of the blood coagulant protein or its binding affinity for a given type of antibody.

The change in activity may be slight or significant, depending upon the nature of the region being replaced as well as the nature of the region being inserted. In fact, the modification may wholly eliminate a biological property of the hybrid protein, which is useful when protein antagonists of natural proteins are desired. An antagonistic hybrid protein would have little or no activity, but still be able to interact with the natural binding partners of the blood coagulation protein from which it is derived and thus prevent the endogenous coagulation factor from interacting with the binding partner.

The hybrid proteins according to the invention are derived from the group of procoagulant proteins. According to the present invention, the procoagulant proteins include Factor V, Factor VIII, Factor X, Factor XIII, fibrinogen, protein S and protein C or any mutant or derivative, including fragments, of any of these proteins. Plasminogen activator inhibitors and plasmin inhibitors are not procoagulant proteins, and thus are not blood coagulation proteins as defined herein.

The acidic regions employed according to the present invention preferably comprise a continuous or nearly continuous region in a protein that usually contains more than 6 and less than 100 amino acids, and includes as many acidic amino acids as to give the region an overall negative charge, that is, at least 15% of the amino acids are acidic amino acids. Preferred acidic amino acids include glutamic acid and aspartic acid.

In one embodiment, the serine protease interaction site is a thrombin binding site and the modification of the blood coagulation protein property primarily refers to the affinity of the protein for prothrombin or thrombin. The affinity of the blood coagulation protein for prothrombin or thrombin may be increased or decreased. Useful blood coagulation proteins whose affinity for thrombin may be modified according to the present invention include Factor V, Factor VIII, protein S or protein C. A modification that effects the affinity of the blood coagulation protein for prothrombin or thrombin may further effect the affinity of the blood coagulation protein for other proteins, such as other procoagulant or anticoagulant proteins or antibodies.

Acidic regions may contain tyrosine residues, which are subject to tyrosine sulfation. Each of charge, acidity and the presence of sulfate-groups in specific regions have an important influence on (i) the three-dimensional structure of the specific region and the whole protein, and (ii) the interaction of the region and/or the whole protein with other factors, like other blood proteins. Important examples of proteins with regions that contain tyrosine residues are various procoagulant and anticoagulant proteins, such as Factor V, Factor VIII, fibrinogen, heparin cofactor II, protein S, protein C or hirudin.

In one embodiment of the present invention, the acidic region of an blood coagulation protein contains one or more tyrosine residues, preferably 1 to 10 tyrosine residues, more preferably 1 to 5 tyrosine residues and most preferably 1 to 3 tyrosine residues.

According to the present invention, one or more acidic regions of an blood coagulation protein may be replaced by one or more acidic regions of one or more donor proteins. For example, an acidic region of a blood coagulation protein may further be replaced by a single acidic region or multiples thereof. Moreover, acidic regions from different proteins may replace a given acidic region or regions in an blood coagulation protein to form a hybrid protein.

According to the present invention, the donor is an anticoagulant or an antithrombotic protein. Preferably, the donor is selected from the group of heparin cofactor II, hirudin or antithrombin or any derivative, including fragments, of any of these proteins. The donor protein may further be a wholly or partially synthetic polypeptide, that is, not derived from a single natural protein, but rather modeled upon rules developed from analyses of families of proteins, as well as the characteristics of individual amino acids.

Replacement of an acidic region in a blood coagulation protein by another acidic region of a donor protein preferably occurs at the DNA level. The DNA may be obtained from genomic DNA or from a cDNA encoding the desired blood coagulation protein and donor protein regions. Replacement can be achieved with PCR and other recombinant DNA methodologies.

The DNA encoding the acidic region of the donor that should replace the acidic region in the blood coagulation protein is either amplified from a gene or from a cDNA or synthesized by a polynucleotide synthesizer. The replacement can be achieved by replacement mutagenesis or by the use of PCR-mutagenesis techniques. PCR-mutagenesis techniques do not require the amplification of the DNA encoding the acidic region from the donor, but rather can use specifically designed PCR primers, which can be synthesized by a polynucleotide synthesizer.

Site-specific and region-directed mutagenesis techniques can be employed. See CURRENT PROTOCOLS IN MOLECULAR BIOLOGY vol. 1, ch. 8 (Ausubel et al. eds., J. Wiley & Sons 1989 & Supp. 1990-93); PROTEIN ENGINEERING (Oxender & Fox eds., A. Liss, Inc. 1987). Additionally, linker-scanning and PCR-mediated techniques can be used. See PCR TECHNOLOGY (Erlich ed., Stockton Press 1989); CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, vols. 1 & 2, supra. Protein sequencing, structure and modeling approaches for use with any of the above techniques are disclosed in PROTEIN ENGINEERING, loc. cit. and CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, vols. 1 & 2, supra.

When the donor protein is wholly or partially a synthetic polypeptide, the DNA encoding the complete polypeptide can be synthesized by a polynucleotide synthesizer. Preferably, this DNA carries appropriate adaptors for cloning such that it can be directly used in recombinant DNA technology.

Changes in the amino acid sequence of the hybrid proteins also are contemplated in the present invention. Preferably, only conservative amino acid alterations, using amino acids that have the same or similar properties, are undertaken. Illustrative amino acid substitutions include the changes of: alanine to serine; arginine to lysine; asparagine to glutamine or histidine; aspartate to glutamate; cysteine to serine; glutamine to asparagine; glutamate to aspartate; glycine to proline; histidine to asparagine or glutamine; isoleucine to leucine or valine; leucine to valine or isoleucine; lysine to arginine, glutamine, or glutamate; methionine to leucine or isoleucine; phenylalanine to tyrosine, leucine or methionine; serine to threonine; threonine to serine; tryptophan to tyrosine; tyrosine to tryptophan or phenylalanine; valine to isoleucine or leucine.

Additionally, variants of the hybrid proteins discussed herein can be used according to the present invention. Variants include analogs, homologs, derivatives, muteins and mimetics of the hybrid proteins that retain the ability to cause the beneficial results described herein. The variants can be generated directly from the hybrid proteins themselves by chemical modification, by proteolytic enzyme digestion, or by combinations thereof. Additionally, genetic engineering techniques, as well as methods of synthesizing polypeptides directly from amino acid residues, can be employed.

Non-peptide compounds that mimic the binding and function of parts of the hybrid proteins ("mimetics") can be produced by the approach outlined in Saragovi et al., Science 253: 792-95 (1991). Mimetics are molecules which mimic elements of protein secondary structure. See, for example, Johnson et al.,"Peptide Turn Mimetics" in BIOTECHNOLOGY AND PHARMACY, Pezzuto et al., Eds., (Chapman and Hall, New York, 1993). The underlying rationale behind the use of peptide mimetics is that the peptide backbone of proteins exists chiefly to orient amino acid side chains in such a way as to facilitate molecular interactions. For the purposes of the present invention, appropriate mimetics can be considered to be the equivalent of the hybrid proteins and mutants thereof.

The skilled artisan can routinely insure that such hybrid proteins according to the present invention are suitable for a given task in view of the screening techniques described herein. For example, in the circumstance where hybrid proteins derived from Factor VIII are involved, the screening techniques include tests for a cofactor and procoagulant activities.

In one particular embodiment of the present invention, the blood protein is made by using a Factor VIII molecule, or a derivative thereof, as a blood coagulation protein and human heparin cofactor II as a donor protein. Heparin cofactor II is a glycoprotein in human plasma that inhibits proteases, for example thrombin. Close to its N-terminus (from amino acid residue 51 to amino acid residue 81), heparin cofactor II carries an acidic region that contains two tyrosine sulfation sites. This region is regarded as a potential thrombin-binding site. Van Deerlin et al., J. Biol. Chem. 266: 20223-31 (1991).

In one specific embodiment of the present invention, the region replaced in Factor VIII or a Factor VIII derivative is an acidic region. According to the desired type of modification of the biological activity of Factor VIII, one or two or all three acidic regions of Factor VIII may be replaced. The acidic regions of Factor VIII may be replaced by the acidic region of heparin cofactor II or by any other region of any one of the donor proteins mentioned above, such as heparin cofactor II, antithrombin III or hirudin. If two or more regions in the blood coagulation protein are replaced, the substituting regions may be identical or diverse, and these regions may be from the same donor protein or different donor proteins. Moreover, various types of synthetic polypeptides can be used.

Additionally, a fusion of more than one region may replace a region in an blood coagulation protein. The fused regions may be identical or different, and may be from one or more donor proteins.

It should be noted that the numbers (amino acid positions) given in this disclosure for the various regions of the blood coagulation and donor proteins make up preferred embodiments of the invention. The regions are by no means restricted to the positions given in the description of the invention. Accordingly, the regions may be larger or smaller. The regions, according to the present invention, may further be fragments of defined regions.

In one embodiment of the present invention, the region that is from human heparin cofactor II is an acidic region located between amino acid residues 51 and 81, and substitutes for any of the acidic regions of Factor VIII. The heparin cofactor II acidic region may substitute for one, two or all three acidic regions in the Factor VIII molecule. The acidic region of heparin cofactor II may further be fused to another acidic region, for example to the acidic region of hirudin, prior to replacing a region in the blood coagulation protein.

In another embodiment of the present invention, the acidic region of human heparin cofactor II, located between amino acid residues 51 and 81, substitutes for the acidic region of human Factor VIII that is located between amino acid residues 705 and 740, preferably it is the region from amino acid residue 712 to amino acid residue 737.

In another embodiment of the present invention, the hybrid human Factor VIII is derived from a human factor VIII mutant that lacks a major portion of the B-domain. For example, amino acid residues 51 and 81 of heparin cofactor II can replace an original acidic region normally found between amino acid residues 712 and 737.

Hybrid proteins also are provided that exhibit the biological activity of blood Factor VIII, yet, with increased procoagulant activity compared to cofactor activity. When administered to hemophilia patients, such hybrid proteins can correct the clotting defect by their action in the clotting cascade. Due to their increased procoagulant activity, the hybrid proteins can be administered at a lower dose and at reduced frequency compared to the proteins with Factor VIII activity described in the prior art. This is a great advantage since production as well as therapy costs can be reduced and, most importantly, the risk of raising inhibitory antibodies in hemophiliacs is decreased because more units of Factor VIII activity can be delivered per molecule.

The hybrid proteins with factor VIII activity of the present invention represent an improvement over recombinant Factor VIII molecules with regard to procoagulant activity. In one embodiment, polypeptides with Factor VIII activity disclosed in EP 294 910 are further modified according to the present invention. In this embodiment, the starting point for the construction of hybrid proteins with increased Factor VIII procoagulant activity are deletion mutants of Factor VIII in which a major portion of the B-domain has been deleted. Examples include Factor VIIIdel(868-1562), referred to herein as "Factor VIII dB695" and Factor VIIIdel(741-1668), referred to herein as "Factor VIII dB928."

Construction and sequence of Factor VIII dB695 are disclosed in EP 294 910. In one embodiment, the region from nucleotide 2191 to nucleotide 2266 of Factor VIII dB695 (encoding amino acids 712 to 737) is replaced by the region from nucleotide 208 to nucleotide 298 (encoding amino acids 51 to 80) of human heparin cofactor II. The amino acid numbers given here refer to the amino acid positions in wild-type Factor VIII; nucleotide positions refer to the numbering of wild-type Factor VIII cDNA wherein the first nucleotide of the translation initiation codon is 1. The resulting DNA construct encodes a hybrid Factor VIII referred to as "Factor VIII dB695-HCII."

The DNA construct can be placed under the control of an appropriate promoter element and inserted into an appropriate DNA expression vector. Examples of appropriate promoter elements are SV40-, CMV-, RSV-, LTR-, EBV-, b-actin-, hGH-, T4-, T3-, T7-, SP6-, metallothionein- Adeno-2, Adeno major late- or TK promoter or muscle specific promoters like the myosin promoters or inducible promoters like hsp- or β-interferon promoter or promoters from steroid hormone responsive genes. Examples of appropriate DNA expression vector systems include pBPV, pSVL, pRc/CMV, pRc/RSV, myogenic vector systems (WO 93/09236) or vectors based upon viral systems, such as poxviruses (see U.S. Pat. No. 5,445,953), adenoviruses, retroviruses or baculo viruses.

The expression vector that carries the DNA construct encoding Factor VIII dB695-HCII may be used to transform a host cell. The host cell may then be grown in a cell culture system to express the protein from the DNA. Factor VIII dB695-HCII is then isolated and purified from the progeny of the host cell or the cell culture medium used to grow the host cell. The host cell may either be a eukaryotic or a prokaryotic cell. Preferred prokaryotic hosts include E. coli and B. subtilis. Preferred eukaryotic hosts include lower eukaryotic cells, as well as mammalian cells. Preferred lower eukaryotic cells include Saccharomyces, Schizosaccharomyces, Kluyveromyces and Pichia. Preferred mammalian cells include CHO, COS, BHK, SK-HEP, C127, MRC5, 293, VERO cells, fibroblasts, keratinocytes or myoblasts, hepatocytes or stem cells, for example hematopoietic stem cells.

Factor VIII dB695-HCII is an inventive improvement of its predecessor molecule, Factor VIII dB695. Factor VIII dB695-HCII retains the desirable characteristics of Factor VIII dB695, which has already been a great improvement over the previously-existing recombinant Factor VIII molecules (EP 294 910). Factor VIII dB695-HCII has capabilities that its precursor does not have, however. The procoagulant activity of Factor VIII dB695-HCII is significantly increased compared to cofactor activity, which is a property imparted by the acidic region of heparin cofactor II.

The present invention also provides fragments and mutants of Factor VIII dB695-HCII as well as fusion proteins comprising functional portions of Factor VIII dB695-HCII, including procoagulant activity.

The present invention also provides fusion proteins, wherein Factor VIII dB695-HCII is fused to another protein or a portion of another protein. For example, Factor VIII dB695-HCII may be fused to a stabilizing portion of a serum albumin or it may be fused to a pre-pro- or pro-sequence derived from another blood factor, like Factor IX or protein S.

The invention further provides dimers and chimers of Factor VIII dB695-HCII, namely compounds having at least one biological activity of Factor VIII dB695-HCII linked to another region having substantially the same amino acid sequence as Factor VIII dB695-HCII. The individual components of a chimer may have differing amino acid sequences. Biological activity includes the ability, when administered to patients with hemophilia A, to correct the clotting defect at lower dose and with a decreased clotting time when compared to the naturally occurring Factor VIII.

To provide immunogenicity, the various Factor VIII dB695-HCII and the Factor VIII dB695-HCII molecules according to the invention may be joined covalently to a large immunogenic polypeptide entity. Such immunogenic entities are, for example, bovine serum albumin, keyhole limpet hemocyanin (KLH) and the like. These conjugated polypeptides will be used for inducing antibodies in an appropriate host organism.

According to the present invention, a full length Factor VIII cDNA, as well as any derivatives thereof, can be used as a starting material for the construction of Factor VIII/heparin cofactor II hybrids. Factor VIII cDNA, as well as any derivative thereof, may originate from any mammalian species, preferably from human, porcine or bovine sources. All forms of manipulation and application described for Factor VIII dB695-HCII apply for any Factor VIII/heparin cofactor II hybrid and are part of the instant disclosure.

In another embodiment, the present invention provides a hybrid protein, wherein the blood coagulation protein is human blood coagulation Factor VIII, or any derivative thereof, and the donor protein is hirudin. Preferably, the acidic region of hirudin, located between amino acids Phe⁵³ and Gln⁶², replaces the acidic region of Factor VIII dB695 located between amino acid residues 705 and 740, preferably it is the acidic region from amino acid 718 to amino acid 732. The resulting hybrid protein is termed Factor VIII dB695-HIR.

Hirudin is a very potent inhibitor of thrombin and it carries a thrombin binding site with a high affinity for thrombin. Due to the replacement, Factor VIII obtains the thrombin binding site of hirudin, and acquires a high affinity for thrombin. Hirudin is the thrombin-specific anticoagulant from the leech Hirudo medicinalis. Although hirudin is not obtained from a mammalian system, it is considered to be an important antithrombotic factor.

The present invention further provides nucleic acids that encode any of the hybrid proteins according to the present invention. The nucleic acid may be DNA or RNA. The nucleic acid is contained in an expression vector that provides the appropriate elements for the expression of the DNA or RNA. The expression vector may also contain elements for the replication of said DNA or RNA. The expression vector may be a DNA or an RNA vector. Examples for DNA expression vectors are pBPV, pSVL, pRc/CMV, pRc/RSV, myogenic vector systems (WO 93/09236) or vectors based upon viral systems, for example, poxviruses (see U.S. Pat. No. 5,445,953), adenoviruses, adeno-associated virus, herpes viruses, retroviruses or baculo viruses. Examples for RNA expression vectors are vectors based upon RNA viruses like retroviruses or flaviviruses.

For gene therapy applications, the nucleic acid encoding the hybrid protein is placed within the mammal. The nucleic acids used in the genetic therapy may be chemically modified. The chemical modifications may be modifications that protect the nucleic acid from nuclease digest, for example by stabilizing the backbone or the termini. Gene therapy techniques are discussed in Culver et al., Science 256: 1550-52 (1992); Rosenberg et al., Human Gene Therapy 3: 57-75 (1992).

An expression vector containing the nucleic acid which encodes a hybrid protein according to the present invention can be used to transform host cells, which then produce the hybrid proteins. The transformed host cells can be grown in a cell culture system to in vitro produce the hybrid protein. The host cells may excrete the hybrid protein into the cell culture medium from which it can be prepared. The host cells also may keep the hybrid protein inside their cell walls and the hybrid protein may be prepared from the host cells.

The host cells may be cells obtained from mammalian cells, such as fibroblasts, keratinocytes, hematopoietic cells, hepatocytes or myoblasts, which can be transformed in vitro with an expression vector system carrying a nucleic acid according to the present invention and re-implanted into the mammal. The hybrid proteins encoded by the nucleic acid will be synthesized by these cells in vivo and they will exhibit a desired biological activity in the mammal.

In one embodiment of the invention, the mammal is a human patient suffering from hemophilia, the hybrid protein is Factor VIII dB695-HCII, which shows enhanced activation properties.

The nucleic acid encoding hybrid proteins according to the present invention, also may be used to generate transgenic animals, which express the hybrid proteins in vivo. In one embodiment, the transgenic animals may express the hybrid proteins in endogenous glands, for example in mammary glands from which the hybrid proteins are secreted. In the case of the mammary glands, the hybrid proteins can be secreted into the milk of the animals from which the hybrid proteins can be prepared. The animals may be mice, rabbits, cattle, horses, swine, goats, sheep or any other useful animal.

The expression vector containing the nucleic acid which encodes any hybrid protein according to the present invention can further be administered to a mammal without prior in vitro transformation into host cells. The practical background for this type of gene therapy is disclosed in several publications, such as WO 90/11092 and WO 94/28151. The expression vector containing the nucleic acid is mixed with an appropriate carrier, for example a physiological buffer solution and injected into an organ, preferably a skeletal muscle, the skin or the liver of a mammal. The mammal is preferably a human and more preferably a human suffering from a genetic defect, most preferably the human is suffering from a blood clotting disorder.

In one embodiment, the mammal is a human patient suffering from hemophilia and the nucleic acid that is contained in the expression vector encodes Factor VIII dB695-HCII.

The present invention provides a method for the production of antibodies that bind to hybrid proteins according to the invention. The antibodies may be monoclonal or polyclonal. Methods for the production of monoclonal or polyclonal antibodies are well known to those skilled in the art. See ANTIBODIES, A LABORATORY MANUAL, E. Harlow and D. Lane eds., CSH Laboratory (1988) and Yelton et al., Ann. Rev. Biochem. 50: 657-680 (1981). The antibodies can be used to determine the presence or absence of a blood protein according to the present invention or to quantify the concentration of the hybrid protein in a biological sample, for example, in a body fluid or in a cell culture medium. In one particular embodiment, said antibodies may bind to Factor VIII dB695-HCII or to Factor VIII dB695-HIR and can be used to determine the presence or absence of Factor VIII dB695-HCII or Factor VIII dB695-HIR or to quantify the concentration of Factor VIII dB695-HCII or Factor VIII dB695-HIR in a biological sample, for example in a body fluid or in a cell culture medium.

The present invention further provides a diagnostic kit that comprises antibodies that bind to hybrid proteins according to the invention. Such kits may further comprise instructions for use and other appropriate reagents, preferably a means for detecting antibodies bound to their substrate. The diagnostic kit may be used to detect the presence of a hybrid protein according to the present invention in a biological sample, such as blood, serum, plasma or urine or in a cell culture medium. It may be further used to quantify the amount of a hybrid protein according to the present invention in a biological sample, such as blood, serum, plasma or urine or in a cell culture medium.

According to the present invention, pharmaceutical compositions are provided, which include the hybrid proteins in a pharmaceutically-acceptable carrier. Pharmaceutically-acceptable carriers include aqueous solutions, non-toxic excipients, including salts, preservatives, buffers and the like, as described in REMINGTON'S PHARMACEUTICAL SCIENCES, 15th Ed. Easton: Mack Publishing Co. pp 1405-1412 and 1461-1487 (1975) and THE NATIONAL FORMULARY XIV., 14th Ed. Washington: American Pharmaceutical Association (1975), the contents of which are hereby incorporated by reference. Examples of non-aqueous solvents are propylene glycol, polyethylene glycol, vegetable oil and injectable organic esters such as ethyloleate. Aqueous carriers include water, alcoholic/aqueous solutions, saline solutions, parenteral vehicles such as sodium chloride, Ringer's dextrose, etc. Intravenous vehicles include fluid and nutrient replenishers. Preservatives include antimicrobials, anti-oxidants, chelating agents and inert gases. The pH and exact concentration of the various components of the binding composition are adjusted according to routine skills in the art. See GOODMAN AND GILMAN'S THE PHARMACOLOGICAL BASIS FOR THERAPEUTICS (7th ed.). Finally, pharmaceutical compositions can include polynucleotides encoding the hybrid proteins or transformed cell comprising these polynucleotides, both of which are usually employed in the genetic therapy context.

The various pharmaceutical compositions according to the invention can be used for treating patients. These compositions include the nucleic acids encoding the hybrid proteins and the transformed mammalian cells which are capable of expressing the hybrid proteins in vivo, as well as the hybrid proteins themselves. The term "treating" in its various grammatical forms in relation to the present invention refers to preventing, curing, reversing, attenuating, alleviating, minimizing, suppressing or halting the deleterious effects of a disease state or progression or other type of abnormal state.

Patients suffering from permanent or temporary coagulation disorders can be treated with hybrid proteins derived from appropriate procoagulant proteins. For example, patients subject to hemophilia should be treated with hybrid proteins derived from Factor VIII or mutants of Factor VIII, such as Factor VIII dB695-HCII, Factor VIII dB695-HIR or any mutants thereof.

The compounds, including hybrid proteins, nucleic acids and transformed cells, as they are provided by the present invention can be used in a wide variety of in vivo and in vitro contexts. The subject compounds may be used as the active component of pharmaceutical compositions for treating patients exhibiting blood clotting deficiencies, preferably hemophilia and more preferably hemophilia A. A pharmaceutical preparation refers to any preparation to be administered to animals.

In the embodiments where the compound is a nucleic acid or a transformed cell, hybrid proteins are synthesized in vivo. All the information required for this in vivo synthesis is contained within the nucleic acid or the transformed cell. For example, a subject having undergone "genetic therapy" will have the hybrid protein appearing in the circulation, where the protein then can alleviate the symptoms associated with blood clotting deficiencies, such as hemophilia.

In preparing the pharmaceutical composition, generally the compounds are admixed with parenterally acceptable vehicles or other suitable carriers in accordance with procedures known in the art. The pharmaceutical composition, where the compound is a hybrid protein or a nucleic acid encoding such a protein, may be made into a sterile lyophilized preparation of the compound, which later may be reconstituted by addition of a sterile solution, preferably one that is isotonic with the blood of the recipient. When the compound is a transformed cell, the compound is admixed with an acceptable isotonic solution and, if necessary, further parenterally acceptable vehicles or other suitable carriers in accordance with procedures known in the art. The pharmaceutical composition may be presented in single unit or multi-dose containers, for example in sealed ampoules or vials. The ultimate use of these hybrid proteins can be based upon the use of known proteins employed to treat blood clotting deficiencies.

When the hybrid protein has a modified Factor VIII procoagulant activity, the use of the compound would be based upon that of known human Factor VIII preparations, appropriately adjusted for potency. The dose of human Factor VIII preparations as it is described in the prior art is dependent on the nature, extent and duration of the bleeding lesion as well as on the severity of the hemophilia. In general, the initial dose lies between 15 and 50 U/kg of body weight. Further administration of more or less reduced doses follow in intervals from 8 hours to several days. Hybrid proteins with modified Factor VIII procoagulant activity may deviate from the dosages needed for wild-type Factor VIII. Hybrid proteins with increased Factor VIII procoagulant activity may be employed at a reduced dose compared to wild-type Factor VIII, the initial dose lying between 1 and 100 U/kg, preferably between 1 and 50 U/kg of body weight. Additionally, the length of time between administrations may be increased. Ultimately, the reduction in dose and the increase of time between intervals of administration have to be decided individually by the attending physician.

The compound may be administered in vivo, for example by injection, intravenously, peritoneally, cutaneously, subcutaneously, or any other appropriate delivery route or mode.

Herein, data from two different test systems are used to describe Factor VIII activity. The "One Stage Clotting Assay" measures the clotting time with the effect from the addition of Factor VIII to Factor VIII deficient plasma. Principally, this test system represents an in vitro equivalent to in vivo blood clotting. Data obtained from this test depend on the ability of Factor VIII to be activated by thrombin. This ability of a Factor VIII molecule to be activated by thrombin directly affects the clotting time that is measured by the assay. The longer it takes to activate Factor VIII, the longer is the clotting time measured. In this document, Factor VIII activity is thus defined as a measurement by the One Stage Clotting Assay as "procoagulant activity."

In contrast to the One Stage Clotting Assay, the "Coatest Chromogenic Assay" measures one specific enzymatic function downstream of Factor VIII in the clotting cascade, that is, Factor Xa activity. Factor VIIIa, which is activated Factor VIII, acts as a cofactor in the activation of Factor X by Factor IXa. Since Factor Xa activity is directly dependent on Factor VIIIa cofactor activity, "Factor VIII cofactor activity" refers to the amount of Factor VIIIa in a sample.

The invention is further illustrated by the following examples, which do not limit the invention in any manner.

EXAMPLE 1

Modification of the construct pCLB-BPVdB695

A cDNA encoding Factor VIII dB695 was cloned into the plasmid pBPV (Pharmacia-LKB, Uppsala, Sweden) resulting in the plasmid pCLB-BPVdB695. Plasmid pCLB-BPVdB695 was modified as follows: a synthetic, double-stranded oligonucleotide linker (SEQ ID NO 3: sense primer: 5'-TCGACCTCCAGTTGAACATTTGTAGCAAGCCACCATGGAAATAGAGCT-3'; SEQ ID NO 4: anti-sense primer: 5'-CTATTTCCATGGTGGCTTGCTACAAATGTTCAACTGGAGG-3') containing part of the 5' untranslated region of the Factor VIII cDNA linked to a consensus-sequence for initiation of translation was fused to the restriction-site SacI at position 10 of the Factor VIII cDNA (the first nucleotide of the translation initiation codon corresponds to nucleotide 1). Introduction of this particular linker into the Factor VIII cDNA resulted in a substitution of glutamine for a glutamic acid at amino acid position-18 (the first amino acid of Factor VIII is the alanine beyond the signal sequence cleavage site). The 3' end of the Factor VIII dB695 cDNA was modified by using a synthetic double stranded linker (sense primer SEQ ID NO 5: 5'-GGGTCGACCTGCAGGCATGCCTCGAGCCGC-3'; anti-sense primer SEQ ID NO 6: 5'-GGCCGCGGCTCGAGGCATGCCTGCAGGTCGACCCTGCA-3'), which was inserted into the PstI-site at nucleotide position 7066 of Factor VIII. This modification resulted in an abridged 3' non-coding region of the Factor VIII cDNA. Both the modified 5' and 3' ends were cloned into the plasmid pBPV, which had been digested with XhoI and NotI. The resulting plasmid was termed pCLB-dB695 and served as starting material for the construction of modified Factor VIII proteins.

According to the present invention, the modified plasmid pCLB-dB695 can be used as a template for the construction of Factor VIII hybrids which contain amino acid sequences from a donor protein. DNA sequences encoding the amino acid sequences from a donor protein are inserted into the Factor VIII dB695 coding region of pCLB-dB695, either in addition to the sequence encoding Factor VIII dB695 or substituting for a portion thereof. Insertion of these sequences leads to Factor VIII hybrid proteins with modified activity, such as increased procoagulant activity.

EXAMPLE 2

Isolation of a part of human heparin cofactor II from liver cDNA

For the isolation of a part of heparin cofactor II cDNA from liver cDNA, PCR technology was employed. The oligonucleotide primers used in the PCR contained portions of the Factor VIII cDNA.

The primers used for amplification of the cDNA fragment encoding the region from Ile⁵¹ to Ser⁸¹ of heparin cofactor II from total liver cDNA were: sense primer SEQ ID NO 7: 5'-CTGAAGGTTTCTAGTTGT/ATTCCAGAGGGGGAGGAG-3' (position 2173-2191 in Factor VIII cDNA/position 208-226 in heparin cofactor II cDNA) and antisense primer SEQ ID NO 8: 5'-GGAGAAGCTTCTTGGTTCAAT/CAGACTGTCGACGATGTC-3' (position 2266-2287 in Factor VIII cDNA/position 280-298 in heparin cofactor II cDNA. The slash ("/") represents the border between Factor VIII and heparin cofactor II originated sequences).

The first nucleotides of Factor VIII cDNA and heparin cofactor II cDNA correspond to the first nucleotide of the translation initiation codon of the two proteins, respectively. According to the numbering system employed herein, position 2173-2191 corresponds to a sequence that includes nucleotides 2173 up to 2190, but does not include nucleotide 2191. The same system of numbering is employed for the amino acids. This numbering system is employed throughout this application.

The polymerase chain reaction (PCR) was used to amplify a 129 bp fragment that contained a fusion of amino acid sequence Leu⁷⁰⁶ -Asp⁷¹² (up to but not including Asp⁷¹²) of Factor VIII, amino acid sequence Ile⁵¹ -Ser⁸¹ (up to but not including Ser⁸¹) of heparin cofactor II and amino acid sequence Ile⁷³⁷ -Gln⁷⁴⁴ (up to but not including Gln⁷⁴⁴) of Factor VIII. Reaction conditions were: 2' 90° C., 20'50° C., 3' 72° C.; 37 times 45" 90° C., 90" 50° C., 3' 72° C.; 5' 65° C. ('=minutes, "=seconds) in the presence of 1 mM dNTPs, Pfu-polymerase reaction buffer, 50 pMol of the sense primer SEQ ID NO 7, 50 pM of the antisense primer SEQ ID NO 8 and 2.5 U of Pfu-polymerase (Stratagene, Cambridge, UK). Human liver cDNA was prepared as described previously (Leyte et al., J. Biochem. 263: 187-94 (1989) and used as a template. The PCR-product was a 129 bp fragment representing an in frame fusion of a portion of Factor VIII and a portion of heparin cofactor II.

EXAMPLE 3

Fusion of Factor VIII heparin cofactor II sequence with pCLB-dB695

In the previous example, the isolation of a fragment of the heparin cofactor II cDNA is described using oligonucleotide primers that are at least partially based upon the Factor VIII cDNA. Employing these specific primers, the portion of the heparin cofactor II cDNA that has been isolated can be introduced at a specific site in the Factor VIII cDNA. Using modifications of the methods described in this example, other cDNA sequences may be fused with the Factor VIII cDNA. Additionally, fusions at sites different from that indicated in this particular example may be used.

The PCR primers employed to insert the Factor VIII/heparin cofactor II fusion site into pCLB-dB695 were the sense primer SEQ ID NO 9: 5'-TCTAGCTTCAGGACTCATTGG-3' (nucleotide 1683-1704 of Factor VIII) and the antisense primer SEQ ID NO 10: 5'-ATACAACTAGAAACCTTCAG-3' (nucleotide 2173-2191 of Factor VIII and nucleotide 208-210 of heparin cofactor II).

The polymerase chain reaction was used to amplify a 510 bp fragment that contained nucleotide 1683-2191 of Factor VIII and nucleotide 208-210 of heparin cofactor II. Reaction conditions were: 2' 90° C., 20' 50° C., 3' 72° C.; 37 times 45" 90° C., 90" 50° C., 3' 72° C.; 5' 65° C. in the presence of 1 mM dNTPs, Pfu-polymerase reaction buffer, 50 pMol of sense primer (1683-1704) SEQ ID NO 9 and 50 pMol of antisense primer (2173-2191) SEQ ID NO 10 and 2.5 U of Pfu-polymerase (Stratagene, Cambridge, UK). Both the 510 bp fragment, as well as the 129 bp fragment described in Example 2, were purified by low-melting agarose followed by phenol extraction and ethanol precipitation. Subsequently, 1 ng of both fragments were used as a template for the polymerase chain reaction employing the above PCR primers SEQ ID NO 9 and SEQ ID NO 8. Reaction conditions were: 2' 90° C., 20' 50° C., 3' 72° C.; 37 times 45" 90° C., 90" 50° C., 3' 72° C.; 5' 65° C. in the presence of 1 mM dNTPs, Pfu-polymerase reaction buffer, 50 pMol of primer SEQ ID NO 9 and SEQ ID NO 8 and 2.5 U of Pfu-polymerase (Stratagene, Cambridge, UK). The resulting fragment of 619 bp was digested with BamHI and HindIII, resulting in a 423 bp fragment in which the region of Factor VIII from nucleotide 2191 to 2266 of Factor VIII was replaced by the region from nucleotide 208 to 298 of heparin cofactor II. The 423 bp BamHI-HindIII fragment which contained the hybrid Factor VIII-heparin cofactor II-sequence was used to replace the corresponding fragment of pCLB-dB695. Following transformation into E. coli DH1, clones containing the Factor VIII dB695-heparin cofactor II fusion cDNA were selected based upon restriction digestion analysis. The resulting plasmid was termed pCLB-dB695-HCII and the sequence of the 423 bp fragment that contained the sequence obtained from heparin cofactor II was verified by oligonucleotide sequencing. The complete sequence of the Factor VIII dB695-HCII cDNA and the amino acid sequence it codes for are depicted in FIGS. 7A-7N.

EXAMPLE 4

Expression of pCLB-dB695 and pCLB-dB695-HCII in C127 cells

In Example 3, the construction of a cDNA encoding a hybrid protein having amino acid sequences obtained from Factor VIII and heparin cofactor II is outlined. The resulting cDNA was cloned into plasmid pBPV, which is commonly used for expression of proteins in eukaryotic cells. Here, the methods for expression of proteins encoded by pCLB-dB695-HCII and pCLB-dB695 in C127 cells are discussed. Similarly, other eukaryotic and prokaryotic cells may be used for the expression of different cDNAs encoding hybrid Factor VIII proteins.

C127 cells were maintained in Iscove's medium supplemented with 10% fetal calf serum, 100 U/ml penicillin and 100 mg/ml streptomycin. Subconfluent monolayers of C127 cells were transfected by the CaPO₄ -method, essentially as described in Graham et al. Virology 52: 456-67 (1973). Both plasmids, pCLB-dB695-HCII (20 μg) as well as pCLB-dB695 (20 μg) were cotransfected with pPGKhyg (1 μg; Ten Riele et al., Nature 348: 649-51 (1990). Following transfection and selection of transfected cells with 200 μg/ml of hygromycin, individual clones were isolated and propagated in selective medium. The secretion of Factor VIII was monitored by measuring the ability of Factor VIII to function as a cofactor for the Factor IXa-dependent conversion of Factor Xa, employing a chromogenic substrate for Factor Xa (Coatest Factor VIII, Chromogenix, Molndal, Sweden).

Factor VIII antigen was determined using monoclonal antibodies that have been characterized previously (Lenting et al., J. Biol. Chem. 269: 7150-55 (1994). Monoclonal antibody CLB-Cag 12, directed against the Factor VIII-light chain was used as a solid phase, while peroxidase-labelled monoclonal antibody CLB-Cag117, also directed against the Factor VIII light-chain, was used to quantify the amount of immobilized Factor VIII. As a standard, normal plasma obtained from a pool of 40 healthy donors was used. Procoagulant activity was determined in a one-stage clotting assay, using congenitally Factor VIII-deficient plasma. Prior to analysis, conditioned medium was mixed with 1/5 volume of a 3.8% sodium citrate solution and diluted at least 5-fold before testing in the coagulation assay. Clones of cells that produced significant amounts of Factor VIII dB695 or Factor VIII dB695 HCII, respectively, were selected for further analysis. The proteins that were expressed by the selected cell clones were analyzed by the methods described above.

Mertens et al., Brit. J. Haematol. 85: 133-42 (1993), have described the properties of Factor VIII del(868-1562), referred to here as "Factor VIII dB695." One clone obtained from cells transfected with pCLB-dB695 (clone 14-6521) and one obtained from cells transfected with pCLB-dB695-HCII (clone 14-6310) were grown to confluency and, subsequently, cofactor activity, procoagulant activity and Factor VIII antigen levels were determined in the manner discussed above, and the data are presented in Table I.

                  TABLE I     ______________________________________                                        ratio     Factor VIII             cofactor procoagulant                                Factor VIII                                        procoagulant/     protein activity activity  antigen cofactor activity     ______________________________________     Factor VIII             174 ± 10                      164 ± 32                                177 ± 33                                        0.94 ± 0.19     dB695     Factor VIII             157 ± 13                      267 ± 20                                174 ± 32                                        1.70 ± 0.18     dB695-HCII     ______________________________________

Factor VIII procoagulant activity refers to the activity as measured by a one-stage clotting assay, which relates to the ability of Factor VIII to be activated, whereas Factor VIII cofactor activity refers to the spectrometric assay, which monitors the formation of Factor Xa. Antigen levels were measured with an ELISA that was specific for the Factor VIII light chain. Values are the mean (±standard deviation) of five different samples for each mutant. Factor VIII procoagulant activity, chromogenic activity and antigen are given in mU/ml conditioned medium. The data obtained show that conditioned medium obtained from clone 14-6521 (Factor VIII dB695) and clone 14-6310 (Factor VIII dB695-HCII) displayed similar cofactor activity. Furthermore, Factor VIII antigen levels were similar for Factor VIII dB695 and Factor VIII dB695-HCII. Investigation of the procoagulant properties of both Factor VIII mutants revealed a procoagulant activity for Factor VIII dB695 that was roughly equivalent to its cofactor activity and antigen levels. Surprisingly, the pro-coagulant activity of Factor VIII dB695-HCII was 1.7 times higher then the activity found in the cofactor activity assay and antigen levels. The increased procoagulant activity of Factor VIII dB695-HCII can be explained by a lower activation threshold, which would not have been expected in view of the scientific literature. Factor VIII dB695-HCII is activated at a lower thrombin level than other known molecules with Factor VIII activity.

This ability to be activated with lower levels of thrombin is demonstrated in Table III (see below). Factor VIII dB695-HCII is activated approximately eight times faster than Factor VIII dB695. Consequently, at a site of vascular injury, any amount of thrombin generated results in the increased activation of Factor VIII dB695-HCII, enabling this molecule to act as a procoagulant compound with an increased efficiency compared to other compounds with Factor VIII activity. In other words, Factor VIII dB695-HCII is activated at a much earlier timepoint in the events of blood coagulation. As a consequence, Factor VIII dB695-HCII can be administered to hemophilia A patients at a much lower dose and at a reduced frequency than other molecules with Factor VIII activity. This highly reduces the risk of inhibitory antibody production in the patients. This further reduces production and medication costs.

EXAMPLE 5

Detection of the Factor VIII dB695-HCII cDNA in stably transfected C127 cells

In the previous examples, the construction, expression and characterization of the hybrid protein Factor VIII dB695-HCII have been described. To verify the sequence of the Factor VIII dB695-HCII hybrid protein in C127 cells stably transfected with pCLB-dB695-HCII (clone 14-6310), DNA was isolated from this particular cell line and a fragment of the inserted Factor VIII cDNA that contained the heparin cofactor II-sequence was PCR amplified with help of the PCR using the following oligonucleotide primers: sense primer SEQ ID NO 11: 5'-GTAGATCAAAGAGGAAACCAG-3' (nucleotide 1732-1753 of Factor VIII) and antisense primer SEQ ID NO 12: 5'-GTCCCCACTGTGATGGAGC-3' (nucleotide 2577-2596 of Factor VIII). PCR conditions were: 2' 90° C., 5' 50° C., 3' 72° C.; 37 times 45" 90° C., 90" 50° C., 3' 72° C.; 5' 65° C. in the presence of 1 mM dNTPs, Taq-polymerase reaction buffer, 50 pMoles of sense primer, 50 pMoles of antisense primer, and 2.5 U of Taq-polymerase. The resulting 879 bp fragment was cloned into the PGEM-T vector (Promega, Madison, Wis.) and the sequence of the insert was determined employing Taq DNA polymerase (Promega, Madison, Wis.). Inspection of the nucleotide sequence of the amplified fragment revealed that the Factor VIII-heparin cofactor II fusion site was present in the cell line. No nucleotide substitutions compared to the nucleotide sequence of the Factor VIII dB695-HCII DNA as depicted in FIGS. 7A-7N were detected.

EXAMPLE 6

Characterization and processing of purified Factor VIII dB695-HCII and Factor VIII dB695

As shown in example 4, the hybrid protein Factor VIII dB695-HCII present in the conditioned medium of cells transfected with pCLB-dB695-HCII displays an increased procoagulant activity compared to Factor VIII dB695. Further characterization of Factor VIII dB695-HCII was performed following purification from conditioned medium of transfected cells. Purification was performed by immuno-affinity chromatography essentially as described in Mertens et al., Brit. J. Haematol. 85: 133-42 (1993). First, the procoagulant and cofactor activities of the purified Factor VIII dB695-HCII was assessed and compared to purified Factor VIII dB695. The results are shown below in Table II.

                  TABLE II     ______________________________________                  procoagulant activity                                 cofactor activity     Factor VIII  (U/ml; n = 3)  (U/ml; n = 4)     ______________________________________     Factor VIII dB695-HCII                  185 ± 14    105 ± 35     Factor VIII dB695                   95 ± 38     96 ± 25     ______________________________________

Cofactor activity and procoagulant activity were determined as described previously. Mertens et al., Brit. J. Haematol. 85: 133-142 (1993). Values are given as the mean (±standard deviation) of different samples (n=number of different samples). The data in table II show that the ratio of procoagulant activity over cofactor activity is 1.8 for Factor VIII dB695-HCII and 1.0 for Factor VIII dB695. In agreement with the data obtained in the conditioned media of the transfected cells purified Factor VIII dB695-HCII displays an increased procoagulant activity.

Next, the subunit composition of Factor VIII dB695-HCII and compared it to the subunit composition of purified Factor VIII dB695 was determined. Gel electrophoresis with a 7.5% SDS-PAGE, followed by immunoblotting with monoclonal and polyclonal antibodies directed against various domains of Factor VIII, was performed for both proteins. Antibodies: CLB-CAg 69; MAS530; pA2 (an affinity-purified polyclonal antibody directed against a peptide that corresponds to amino acid sequence Ile⁴⁸⁰ -Leu⁴⁹⁸ of Factor VIII) and CLB-CAg 9 were employed. The data indicated that Factor VIII dB695-HCII is processed properly into a light and a heavy chain and its subunit composition is the same as that of Factor VIII dB695.

Monoclonal antibody CLB-CAg69, directed against the amino-acid sequence Lys¹⁶⁷³ -Arg¹⁶⁸⁹ at the amino-terminus of the Factor VIII light chain, revealed the presence of two bands that correspond to the Factor VIII light chain and single chain unprocessed Factor VIII, respectively.

Monoclonal antibody MAS530 (Sera-Lab, Sussex, England) directed against the heavy chain of Factor VIII, recognizes single chain Factor VIII dB695-HCII and in addition reacts with several other bands which represent the Factor VIII heavy chain with variable portions of the Factor VIII B-domain attached. Immunoblot analysis of purified Factor VIII dB695 with the same monoclonal antibodies yields identical results.

An affinity-purified polyclonal antibody directed against a synthetic peptide that corresponds to Ile⁴⁸⁰ -Leu⁴⁹⁸ of Factor VIII was found to react in a similar manner as monoclonal antibody MAS530. Monoclonal antibody CLB-CAg 9 is directed against the peptide Asp⁷²¹ -Asn735, a sequence that is not present in Factor VIII dB695-HCII. As expected, Factor VIII dB695-HCII does not react with this particular antibody. In contrast, purified Factor VIII dB695 readily reacts with monoclonal antibody CLB-CAg 9 and the pattern obtained is identical to that obtained for monoclonal antibody MAS530 which is also directed against the Factor VIII heavy chain.

These results show that proteolytic processing and subunit composition of Factor VIII dB695-HCII is identical to Factor VIII dB695. The difference between Factor VIII dB695 and Factor VIII dB695-HCII, however, is the surprisingly increased procoagulant activity of the hybrid protein. Therefore, these data indicate that Factor VIII dB695-HCII can be used as an improved reagent for the treatment of the congenital bleeding disorder hemophilia A.

EXAMPLE 7

Thrombin activation of Factor VIII dB695-HCII and Factor VIII dB695

Examples 4 and 6 show that Factor VIII dB695-HCII displays an increased procoagulant activity compared to Factor VIII dB695. Determination of the second-order rate constant of cleavage by thrombin for both Factor VIII dB695-HCII and Factor VIII dB695, as it is depicted in FIG. 5, has further shown that less thrombin is required to activate Factor VIII dB695-HCII compared to Factor VIII dB695.

Activation of Factor VIII was determined employing the following reagents. Phospholipid vesicles were prepared from equimolar concentrations of L-a-phosphatidylcholine (egg yolk) and L-a-phosphatidylserine (human brain) (Sigma, St. Louis, U.S.A.). Factor IXa, thrombin, Factor X and Factor Xa were prepared as described previously and the concentration of the different protein preparations was determined by active-site titration (Mertens et al., J. Biochem. 223: 599-605 (1984)). Proteins used in this study were homogeneous as judged by SDS-polyacrylamide gel electrophoresis. Factor X was acetylated using procedures described previously (Neuenschwander et al., Analyt. Biochem. 184: 347-52 (1990).

Activation of Factor VIII dB695 and Factor VIII dB695-HCII by thrombin was monitored as follows: Phospholipid vesicles (final concentration 100 mM) were allowed to aggregate for 10 min at 37° C. in a Ca²⁺ -containing buffer (50 mM Tris HCl pH=7.5, 150 mM NaCl and 10 mM CaCl₂). Subsequently, 0.1 nM of Factor IXa, 0.2 mM acetylated Factor Xa and 0.5 U/ml Factor VIII were added. Activation of Factor VIII was initiated by the addition of various concentrations of thrombin. The amount of Factor Xa formed in time in the reaction mixture was assessed by sub-sampling 50 ml of the reaction mixture into stop buffer containing 50 mM Tris-HCl pH=7.5, 150 mM NaCl, 5 mM EDTA, 50 U/ml hirudin, 100 mg/ml egg ovalbumin and the synthetic substrate Pefachrome Xa (Pentapharm AG, Basel, Switzerland).

Conversion of the substrate Pefachrome Xa was monitored at 405 nm and active-site titrated Factor Xa was used as a standard. In FIG. 3, activation of Factor VIII dB695 is depicted for several concentrations of thrombin. The amount of Factor Xa generated is related to the concentration of thrombin used for activation. Using the following set of reactions, an equation that describes the activation of Factor VIII adequately can be obtained: ##STR1## where K₁ -K₄ constitute the rate constants of the different reaction steps. In Step 1 of this reaction strategy, the activation of Factor VIII by thrombin is depicted. The Factor VIIIa-Factor IXa complex efficiently catalyzes the phospholipid-dependent conversion of Factor X into Factor Xa.

In the experiments performed, phospholipids were used in high concentrations. As a consequence the interaction of the different components with phospholipids is not considered to be rate-limiting. The conversion of Factor X into its activated form (Step 2) is analyzed according to standard Michaelis-Menton kinetics, resulting in the following equation: ##EQU1## where K_(m) =(k₃ +k₄)/k₂ and FX!_(t) = FX!₀. The concentration of Factor VIIIa increases in time from FVIIIa!₀ (=0) to FVIIIa!_(t). By using appropriate concentrations of activator during the initial phase of Factor Xa formation, Factor VIII activation can be analyzed according to the method of initial rates of activation.

     FVIIIA!.sub.t =k.sub.1  FVIII!.sub.0.sup.t                (2)

Combining equation (1) and (2) and subsequent integration between t=0 and t=t results in the following expression of Factor Xa formation in time: ##EQU2## Equation 3 is very similar to the usual solution for a complex kinetic system comprising two coupled enzymatic reaction steps. (Chibber et al., Biochemistry 24: 3429-34 (1985). The values of a number of parameters in Equation 3 are known. The Factor X activation rate constant k4 in the presence of Factor VIII dB695 and Factor VIII dB695 are 11.5±5.2 min³¹ and 17.2 ±5.5 min⁻¹, respectively which have been determined experimentally from the rate of Factor Xa formation at steady state conditions. The Michaelis constant (Km) is 200 nM for human coagulation factors Factor VIIIa and Factor IXa (Jesty, Haemostasis 21: 208-18 (1991) and FVIII!₀ =0.2 nM and FX!₀ =0.2 mM. The data obtained were fitted into Equation 3 using Enzfitter software (Elsevier, The Netherlands). For each thrombin concentration used to activate Factor VIII dB695, a first order constant can be obtained that is dependent on the thrombin concentration employed. The slope of a plot of the thrombin-concentration used for activation of Factor VIII dB695 against the first-order constant (k₁) yields a second-order constant of activation (FIG. 5). In table III, the values of the second-order constant of activation are given for both Factor VIII dB695 and Factor VIII dB695-HCII. The values of the second order constant of activation reveal that Factor VIII dB695-HCII is activated by thrombin eight times as fast as Factor VIII dB695.

                  TABLE III     ______________________________________                        second order rate constant     Factor VIII protein                        (M.sup.-1 s.sup.-1 × 10.sup.-6)     ______________________________________     Factor VIII obtained from plasma                        2.1 ± 0.2     Factor VIII dB695  3.0 ± 0.8     Factor VIII dB695-HCII                        23.2 ± 0.5     ______________________________________

The second-order rate constant of activation of both Factor VIII dB695 and Factor VIII dB695-HCII by thrombin was determined from the slope of FIG. 5. Values are given in M⁻¹ s⁻¹ ±S.E.

EXAMPLE 8

Construction of a Factor VIII-hirudin hybrid protein

This example concerns the construction of a hybrid protein in which the amino acid sequence Tyr⁷¹⁸ -Ser⁷³² of human Factor VIII has been replaced by amino acid sequence Phe⁵⁶ -Gln⁶⁵ of hirudin. The sense primer SEQ ID NO 13 (5'-AGGAAATTCCAGAGGAATATTTGCAGA GTAAAAACAATGCCATT-3') and the antisense primer SEQ ID NO 12 (5'-GTCCCCACT GTGATGGAGC-3') were used to amplify a 371 bp fragment. The part of primer SEQ ID NO 13 that corresponds to hirudin is based upon the amino acid sequence of hirudin. Favorable codons have been selected for the different amino acids and a putative hirudin cDNA has been assembled. Part of the primers used for the construction of the Factor VIII-hirudin hybrid are based upon the putative hirudin cDNA sequence. The sense primer SEQ ID NO 11 and the antisense primer SEQ ID NO 14 (5'-AATATTCCTCTGGAATTTCCTCGAAATCACCAGTGTTCTTGTC-3') were used to amplify a 502 bp fragment. Reaction conditions were: 2' 90° C., 20'50° C., 3'72° C., 37 times 45" 90° C., 90"50° C., 3'72° C., 5' 65° C. in the presence of 1 mM dNTPS, Pfu-polymerase reaction buffer, 50 pMol of sense primer and 50 pMol of antisense primer and 2.5 U of Pfu-polymerase (Stratagene, Cambridge, UK). Both the 502 bp and 371 bp fragment were purified by low-melting agarose, followed by phenol extraction and ethanol precipitation. Subsequently, 1 ng of each fragment was used as a template for the polymerase chain reaction employing primers SEQ ID NO 11 (5'-GTAGATCAAAGAGGAAACCAG-3') and SEQ ID NO 12. Reaction conditions were similar to that described above. The resulting fragment of 852 bp was digested with BamHI and HindIII, resulting in a 396 bp fragment which was used to replace the corresponding fragment of pCLB-dB695. Clones containing cDNA encoding the Factor VIII-hirudin hybrid protein were selected and the resulting plasmid was termed pCLB-dB695-HIR. The sequence of the 396 bp fragment that contained part of the putative hirudin cDNA was verified. FIG. 6 is a schematic representation of the resulting hybrid Factor VIII dB695-HIR protein that is encoded by the plasmid pCLB-dB695-HIR.

It is to be understood that the description, specific examples and data, while indicating preferred embodiments, are given by way of illustration and exemplification and are not intended to limit the present invention. Various changes and modifications within the present invention will become apparent to the skilled artisan from the discussion and disclosure contained herein.

    __________________________________________________________________________     SEQUENCE LISTING     (1) GENERAL INFORMATION:     (iii) NUMBER OF SEQUENCES: 17     (2) INFORMATION FOR SEQ ID NO:1:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 5035 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (ix) FEATURE:     (A) NAME/KEY: CDS     (B) LOCATION: 35..5017     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:     TCGACCTCCAGTTGAACATTTGTAGCAAGCCACCATGGAAATAGAGCTCTCC52     MetGluIleGluLeuSer     15     ACCTGCTTCTTTCTGTGCCTTTTGCGATTCTGCTTTAGTGCCACCAGA100     ThrCysPhePheLeuCysLeuLeuArgPheCysPheSerAlaThrArg     101520     AGATACTACCTGGGTGCAGTGGAACTGTCATGGGACTATATGCAAAGT148     ArgTyrTyrLeuGlyAlaValGluLeuSerTrpAspTyrMetGlnSer     253035     GATCTCGGTGAGCTGCCTGTGGACGCAAGATTTCCTCCTAGAGTGCCA196     AspLeuGlyGluLeuProValAspAlaArgPheProProArgValPro     404550     AAATCTTTTCCATTCAACACCTCAGTCGTGTACAAAAAGACTCTGTTT244     LysSerPheProPheAsnThrSerValValTyrLysLysThrLeuPhe     55606570     GTAGAATTCACGGATCACCTTTTCAACATCGCTAAGCCAAGGCCACCC292     ValGluPheThrAspHisLeuPheAsnIleAlaLysProArgProPro     758085     TGGATGGGTCTGCTAGGTCCTACCATCCAGGCTGAGGTTTATGATACA340     TrpMetGlyLeuLeuGlyProThrIleGlnAlaGluValTyrAspThr     9095100     GTGGTCATTACACTTAAGAACATGGCTTCCCATCCTGTCAGTCTTCAT388     ValValIleThrLeuLysAsnMetAlaSerHisProValSerLeuHis     105110115     GCTGTTGGTGTATCCTACTGGAAAGCTTCTGAGGGAGCTGAATATGAT436     AlaValGlyValSerTyrTrpLysAlaSerGluGlyAlaGluTyrAsp     120125130     GATCAGACCAGTCAAAGGGAGAAAGAAGATGATAAAGTCTTCCCTGGT484     AspGlnThrSerGlnArgGluLysGluAspAspLysValPheProGly     135140145150     GGAAGCCATACATATGTCTGGCAGGTCCTGAAAGAGAATGGTCCAATG532     GlySerHisThrTyrValTrpGlnValLeuLysGluAsnGlyProMet     155160165     GCCTCTGACCCACTGTGCCTTACCTACTCATATCTTTCTCATGTGGAC580     AlaSerAspProLeuCysLeuThrTyrSerTyrLeuSerHisValAsp     170175180     CTGGTAAAAGACTTGAATTCAGGCCTCATTGGAGCCCTACTAGTATGT628     LeuValLysAspLeuAsnSerGlyLeuIleGlyAlaLeuLeuValCys     185190195     AGAGAAGGGAGTCTGGCCAAGGAAAAGACACAGACCTTGCACAAATTT676     ArgGluGlySerLeuAlaLysGluLysThrGlnThrLeuHisLysPhe     200205210     ATACTACTTTTTGCTGTATTTGATGAAGGGAAAAGTTGGCACTCAGAA724     IleLeuLeuPheAlaValPheAspGluGlyLysSerTrpHisSerGlu     215220225230     ACAAAGAACTCCTTGATGCAGGATAGGGATGCTGCATCTGCTCGGGCC772     ThrLysAsnSerLeuMetGlnAspArgAspAlaAlaSerAlaArgAla     235240245     TGGCCTAAAATGCACACAGTCAATGGTTATGTAAACAGGTCTCTGCCA820     TrpProLysMetHisThrValAsnGlyTyrValAsnArgSerLeuPro     250255260     GGTCTGATTGGATGCCACAGGAAATCAGTCTATTGGCATGTGATTGGA868     GlyLeuIleGlyCysHisArgLysSerValTyrTrpHisValIleGly     265270275     ATGGGCACCACTCCTGAAGTGCACTCAATATTCCTCGAAGGTCACACA916     MetGlyThrThrProGluValHisSerIlePheLeuGluGlyHisThr     280285290     TTTCTTGTGAGGAACCATCGCCAGGCGTCCTTGGAAATCTCGCCAATA964     PheLeuValArgAsnHisArgGlnAlaSerLeuGluIleSerProIle     295300305310     ACTTTCCTTACTGCTCAAACACTCTTGATGGACCTTGGACAGTTTCTA1012     ThrPheLeuThrAlaGlnThrLeuLeuMetAspLeuGlyGlnPheLeu     315320325     CTGTTTTGTCATATCTCTTCCCACCAACATGATGGCATGGAAGCTTAT1060     LeuPheCysHisIleSerSerHisGlnHisAspGlyMetGluAlaTyr     330335340     GTCAAAGTAGACAGCTGTCCAGAGGAACCCCAACTACGAATGAAAAAT1108     ValLysValAspSerCysProGluGluProGlnLeuArgMetLysAsn     345350355     AATGAAGAAGCGGAAGACTATGATGATGATCTTACTGATTCTGAAATG1156     AsnGluGluAlaGluAspTyrAspAspAspLeuThrAspSerGluMet     360365370     GATGTGGTCAGGTTTGATGATGACAACTCTCCTTCCTTTATCCAAATT1204     AspValValArgPheAspAspAspAsnSerProSerPheIleGlnIle     375380385390     CGCTCAGTTGCCAAGAAGCATCCTAAAACTTGGGTACATTACATTGCT1252     ArgSerValAlaLysLysHisProLysThrTrpValHisTyrIleAla     395400405     GCTGAAGAGGAGGACTGGGACTATGCTCCCTTAGTCCTCGCCCCCGAT1300     AlaGluGluGluAspTrpAspTyrAlaProLeuValLeuAlaProAsp     410415420     GACAGAAGTTATAAAAGTCAATATTTGAACAATGGCCCTCAGCGGATT1348     AspArgSerTyrLysSerGlnTyrLeuAsnAsnGlyProGlnArgIle     425430435     GGTAGGAAGTACAAAAAAGTCCGATTTATGGCATACACAGATGAAACC1396     GlyArgLysTyrLysLysValArgPheMetAlaTyrThrAspGluThr     440445450     TTTAAGACTCGTGAAGCTATTCAGCATGAATCAGGAATCTTGGGACCT1444     PheLysThrArgGluAlaIleGlnHisGluSerGlyIleLeuGlyPro     455460465470     TTACTTTATGGGGAAGTTGGAGACACACTGTTGATTATATTTAAGAAT1492     LeuLeuTyrGlyGluValGlyAspThrLeuLeuIleIlePheLysAsn     475480485     CAAGCAAGCAGACCATATAACATCTACCCTCACGGAATCACTGATGTC1540     GlnAlaSerArgProTyrAsnIleTyrProHisGlyIleThrAspVal     490495500     CGTCCTTTGTATTCAAGGAGATTACCAAAAGGTGTAAAACATTTGAAG1588     ArgProLeuTyrSerArgArgLeuProLysGlyValLysHisLeuLys     505510515     GATTTTCCAATTCTGCCAGGAGAAATATTCAAATATAAATGGACAGTG1636     AspPheProIleLeuProGlyGluIlePheLysTyrLysTrpThrVal     520525530     ACTGTAGAAGATGGGCCAACTAAATCAGATCCTCGGTGCCTGACCCGC1684     ThrValGluAspGlyProThrLysSerAspProArgCysLeuThrArg     535540545550     TATTACTCTAGTTTCGTTAATATGGAGAGAGATCTAGCTTCAGGACTC1732     TyrTyrSerSerPheValAsnMetGluArgAspLeuAlaSerGlyLeu     555560565     ATTGGCCCTCTCCTCATCTGCTACAAAGAATCTGTAGATCAAAGAGGA1780     IleGlyProLeuLeuIleCysTyrLysGluSerValAspGlnArgGly     570575580     AACCAGATAATGTCAGACAAGAGGAATGTCATCCTGTTTTCTGTATTT1828     AsnGlnIleMetSerAspLysArgAsnValIleLeuPheSerValPhe     585590595     GATGAGAACCGAAGCTGGTACCTCACAGAGAATATACAACGCTTTCTC1876     AspGluAsnArgSerTrpTyrLeuThrGluAsnIleGlnArgPheLeu     600605610     CCCAATCCAGCTGGAGTGCAGCTTGAGGATCCAGAGTTCCAAGCCTCC1924     ProAsnProAlaGlyValGlnLeuGluAspProGluPheGlnAlaSer     615620625630     AACATCATGCACAGCATCAATGGCTATGTTTTTGATAGTTTGCAGTTG1972     AsnIleMetHisSerIleAsnGlyTyrValPheAspSerLeuGlnLeu     635640645     TCAGTTTGTTTGCATGAGGTGGCATACTGGTACATTCTAAGCATTGGA2020     SerValCysLeuHisGluValAlaTyrTrpTyrIleLeuSerIleGly     650655660     GCACAGACTGACTTCCTTTCTGTCTTCTTCTCTGGATATACCTTCAAA2068     AlaGlnThrAspPheLeuSerValPhePheSerGlyTyrThrPheLys     665670675     CACAAAATGGTCTATGAAGACACACTCACCCTATTCCCATTCTCAGGA2116     HisLysMetValTyrGluAspThrLeuThrLeuPheProPheSerGly     680685690     GAAACTGTCTTCATGTCGATGGAAAACCCAGGTCTATGGATTCTGGGG2164     GluThrValPheMetSerMetGluAsnProGlyLeuTrpIleLeuGly     695700705710     TGCCACAACTCAGACTTTCGGAACAGAGGCATGACCGCCTTACTGAAG2212     CysHisAsnSerAspPheArgAsnArgGlyMetThrAlaLeuLeuLys     715720725     GTTTCTAGTTGTATTCCAGAGGGGGAGGAGGACGACGACTATCTGGAC2260     ValSerSerCysIleProGluGlyGluGluAspAspAspTyrLeuAsp     730735740     CTGGAGAAGATATTCAGTGAAGACGACGACTACATCGACATCGTCGAC2308     LeuGluLysIlePheSerGluAspAspAspTyrIleAspIleValAsp     745750755     AGTCTGATTGAACCAAGAAGCTTCTCCCAGAATTCAAGACACCCTAGC2356     SerLeuIleGluProArgSerPheSerGlnAsnSerArgHisProSer     760765770     ACTAGGCAAAAGCAATTTAATGCCACCACAATTCCAGAAAATGACATA2404     ThrArgGlnLysGlnPheAsnAlaThrThrIleProGluAsnAspIle     775780785790     GAGAAGACTGACCCTTGGTTTGCACACAGAACACCTATGCCTAAAATA2452     GluLysThrAspProTrpPheAlaHisArgThrProMetProLysIle     795800805     CAAAATGTCTCCTCTAGTGATTTGTTGATGCTCTTGCGACAGAGTCCT2500     GlnAsnValSerSerSerAspLeuLeuMetLeuLeuArgGlnSerPro     810815820     ACTCCACATGGGCTATCCTTATCTGATCTCCAAGAAGCCAAATATGAG2548     ThrProHisGlyLeuSerLeuSerAspLeuGlnGluAlaLysTyrGlu     825830835     ACTTTTTCTGATGATCCATCACCTGGAGCAATAGACAGTAATAACAGC2596     ThrPheSerAspAspProSerProGlyAlaIleAspSerAsnAsnSer     840845850     CTGTCTGAAATGACACACTTCAGGCCACAGCTCCATCACAGTGGGGAC2644     LeuSerGluMetThrHisPheArgProGlnLeuHisHisSerGlyAsp     855860865870     ATGGTATTTACCCCTGAGTCAGGCCTCCAATTAAGATTAAATGAGAAA2692     MetValPheThrProGluSerGlyLeuGlnLeuArgLeuAsnGluLys     875880885     CTGGGGACAACTGCAGATCCTCTTGCTTGGGATAACCACTATGGTACT2740     LeuGlyThrThrAlaAspProLeuAlaTrpAspAsnHisTyrGlyThr     890895900     CAGATACCAAAAGAAGAGTGGAAATCCCAAGAGAAGTCACCAGAAAAA2788     GlnIleProLysGluGluTrpLysSerGlnGluLysSerProGluLys     905910915     ACAGCTTTTAAGAAAAAGGATACCATTTTGTCCCTGAACGCTTGTGAA2836     ThrAlaPheLysLysLysAspThrIleLeuSerLeuAsnAlaCysGlu     920925930     AGCAATCATGCAATAGCAGCAATAAATGAGGGACAAAATAAGCCCGAA2884     SerAsnHisAlaIleAlaAlaIleAsnGluGlyGlnAsnLysProGlu     935940945950     ATAGAAGTCACCTGGGCAAAGCAAGGTAGGACTGAAAGGCTGTGCTCT2932     IleGluValThrTrpAlaLysGlnGlyArgThrGluArgLeuCysSer     955960965     CAAAACCCACCAGTCTTGAAACGCCATCAACGGGAAATAACTCGTACT2980     GlnAsnProProValLeuLysArgHisGlnArgGluIleThrArgThr     970975980     ACTCTTCAGTCAGATCAAGAGGAAATTGACTATGATGATACCATATCA3028     ThrLeuGlnSerAspGlnGluGluIleAspTyrAspAspThrIleSer     985990995     GTTGAAATGAAGAAGGAAGATTTTGACATTTATGATGAGGATGAAAAT3076     ValGluMetLysLysGluAspPheAspIleTyrAspGluAspGluAsn     100010051010     CAGAGCCCCCGCAGCTTTCAAAAGAAAACACGACACTATTTTATTGCT3124     GlnSerProArgSerPheGlnLysLysThrArgHisTyrPheIleAla     1015102010251030     GCAGTGGAGAGGCTCTGGGATTATGGGATGAGTAGCTCCCCACATGTT3172     AlaValGluArgLeuTrpAspTyrGlyMetSerSerSerProHisVal     103510401045     CTAAGAAACAGGGCTCAGAGTGGCAGTGTCCCTCAGTTCAAGAAAGTT3220     LeuArgAsnArgAlaGlnSerGlySerValProGlnPheLysLysVal     105010551060     GTTTTCCAGGAATTTACTGATGGCTCCTTTACTCAGCCCTTATACCGT3268     ValPheGlnGluPheThrAspGlySerPheThrGlnProLeuTyrArg     106510701075     GGAGAACTAAATGAACATTTGGGACTCCTGGGGCCATATATAAGAGCA3316     GlyGluLeuAsnGluHisLeuGlyLeuLeuGlyProTyrIleArgAla     108010851090     GAAGTTGAAGATAATATCATGGTAACTTTCAGAAATCAGGCCTCTCGT3364     GluValGluAspAsnIleMetValThrPheArgAsnGlnAlaSerArg     1095110011051110     CCCTATTCCTTCTATTCTAGCCTTATTTCTTATGAGGAAGATCAGAGG3412     ProTyrSerPheTyrSerSerLeuIleSerTyrGluGluAspGlnArg     111511201125     CAAGGAGCAGAACCTAGAAAAAACTTTGTCAAGCCTAATGAAACCAAA3460     GlnGlyAlaGluProArgLysAsnPheValLysProAsnGluThrLys     113011351140     ACTTACTTTTGGAAAGTGCAACATCATATGGCACCCACTAAAGATGAG3508     ThrTyrPheTrpLysValGlnHisHisMetAlaProThrLysAspGlu     114511501155     TTTGACTGCAAAGCCTGGGCTTATTTCTCTGATGTTGACCTGGAAAAA3556     PheAspCysLysAlaTrpAlaTyrPheSerAspValAspLeuGluLys     116011651170     GATGTGCACTCAGGCCTGATTGGACCCCTTCTGGTCTGCCACACTAAC3604     AspValHisSerGlyLeuIleGlyProLeuLeuValCysHisThrAsn     1175118011851190     ACACTGAACCCTGCTCATGGGAGACAAGTGACAGTACAGGAATTTGCT3652     ThrLeuAsnProAlaHisGlyArgGlnValThrValGlnGluPheAla     119512001205     CTGTTTTTCACCATCTTTGATGAGACCAAAAGCTGGTACTTCACTGAA3700     LeuPhePheThrIlePheAspGluThrLysSerTrpTyrPheThrGlu     121012151220     AATATGGAAAGAAACTGCAGGGCTCCCTGCAATATCCAGATGGAAGAT3748     AsnMetGluArgAsnCysArgAlaProCysAsnIleGlnMetGluAsp     122512301235     CCCACTTTTAAAGAGAATTATCGCTTCCATGCAATCAATGGCTACATA3796     ProThrPheLysGluAsnTyrArgPheHisAlaIleAsnGlyTyrIle     124012451250     ATGGATACACTACCTGGCTTAGTAATGGCTCAGGATCAAAGGATTCGA3844     MetAspThrLeuProGlyLeuValMetAlaGlnAspGlnArgIleArg     1255126012651270     TGGTATCTGCTCAGCATGGGCAGCAATGAAAACATCCATTCTATTCAT3892     TrpTyrLeuLeuSerMetGlySerAsnGluAsnIleHisSerIleHis     127512801285     TTCAGTGGACATGTGTTCACTGTACGAAAAAAAGAGGAGTATAAAATG3940     PheSerGlyHisValPheThrValArgLysLysGluGluTyrLysMet     129012951300     GCACTGTACAATCTCTATCCAGGTGTTTTTGAGACAGTGGAAATGTTA3988     AlaLeuTyrAsnLeuTyrProGlyValPheGluThrValGluMetLeu     130513101315     CCATCCAAAGCTGGAATTTGGCGGGTGGAATGCCTTATTGGCGAGCAT4036     ProSerLysAlaGlyIleTrpArgValGluCysLeuIleGlyGluHis     132013251330     CTACATGCTGGGATGAGCACACTTTTTCTGGTGTACAGCAATAAGTGT4084     LeuHisAlaGlyMetSerThrLeuPheLeuValTyrSerAsnLysCys     1335134013451350     CAGACTCCCCTGGGAATGGCTTCTGGACACATTAGAGATTTTCAGATT4132     GlnThrProLeuGlyMetAlaSerGlyHisIleArgAspPheGlnIle     135513601365     ACAGCTTCAGGACAATATGGACAGTGGGCCCCAAAGCTGGCCAGACTT4180     ThrAlaSerGlyGlnTyrGlyGlnTrpAlaProLysLeuAlaArgLeu     137013751380     CATTATTCCGGATCAATCAATGCCTGGAGCACCAAGGAGCCCTTTTCT4228     HisTyrSerGlySerIleAsnAlaTrpSerThrLysGluProPheSer     138513901395     TGGATCAAGGTGGATCTGTTGGCACCAATGATTATTCACGGCATCAAG4276     TrpIleLysValAspLeuLeuAlaProMetIleIleHisGlyIleLys     140014051410     ACCCAGGGTGCCCGTCAGAAGTTCTCCAGCCTCTACATCTCTCAGTTT4324     ThrGlnGlyAlaArgGlnLysPheSerSerLeuTyrIleSerGlnPhe     1415142014251430     ATCATCATGTATAGTCTTGATGGGAAGAAGTGGCAGACTTATCGAGGA4372     IleIleMetTyrSerLeuAspGlyLysLysTrpGlnThrTyrArgGly     143514401445     AATTCCACTGGAACCTTAATGGTCTTCTTTGGCAATGTGGATTCATCT4420     AsnSerThrGlyThrLeuMetValPhePheGlyAsnValAspSerSer     145014551460     GGGATAAAACACAATATTTTTAACCCTCCAATTATTGCTCGATACATC4468     GlyIleLysHisAsnIlePheAsnProProIleIleAlaArgTyrIle     146514701475     CGTTTGCACCCAACTCATTATAGCATTCGCAGCACTCTTCGCATGGAG4516     ArgLeuHisProThrHisTyrSerIleArgSerThrLeuArgMetGlu     148014851490     TTGATGGGCTGTGATTTAAATAGTTGCAGCATGCCATTGGGAATGGAG4564     LeuMetGlyCysAspLeuAsnSerCysSerMetProLeuGlyMetGlu     1495150015051510     AGTAAAGCAATATCAGATGCACAGATTACTGCTTCATCCTACTTTACC4612     SerLysAlaIleSerAspAlaGlnIleThrAlaSerSerTyrPheThr     151515201525     AATATGTTTGCCACCTGGTCTCCTTCAAAAGCTCGACTTCACCTCCAA4660     AsnMetPheAlaThrTrpSerProSerLysAlaArgLeuHisLeuGln     153015351540     GGGAGGAGTAATGCCTGGAGACCTCAGGTGAATAATCCAAAAGAGTGG4708     GlyArgSerAsnAlaTrpArgProGlnValAsnAsnProLysGluTrp     154515501555     CTGCAAGTGGACTTCCAGAAGACAATGAAAGTCACAGGAGTAACTACT4756     LeuGlnValAspPheGlnLysThrMetLysValThrGlyValThrThr     156015651570     CAGGGAGTAAAATCTCTGCTTACCAGCATGTATGTGAAGGAGTTCCTC4804     GlnGlyValLysSerLeuLeuThrSerMetTyrValLysGluPheLeu     1575158015851590     ATCTCCAGCAGTCAAGATGGCCATCAGTGGACTCTCTTTTTTCAGAAT4852     IleSerSerSerGlnAspGlyHisGlnTrpThrLeuPhePheGlnAsn     159516001605     GGCAAAGTAAAGGTTTTTCAGGGAAATCAAGACTCCTTCACACCTGTG4900     GlyLysValLysValPheGlnGlyAsnGlnAspSerPheThrProVal     161016151620     GTGAACTCTCTAGACCCACCGTTACTGACTCGCTACCTTCGAATTCAC4948     ValAsnSerLeuAspProProLeuLeuThrArgTyrLeuArgIleHis     162516301635     CCCCAGAGTTGGGTGCACCAGATTGCCCTGAGGATGGAGGTTCTGGGC4996     ProGlnSerTrpValHisGlnIleAlaLeuArgMetGluValLeuGly     164016451650     TGCGAGGCACAGGACCTCTACTGAGGGTGGCCACTGCAG5035     CysGluAlaGlnAspLeuTyr     16551660     (2) INFORMATION FOR SEQ ID NO:2:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 1661 amino acids     (B) TYPE: amino acid     (D) TOPOLOGY: linear     (ii) MOLECULE TYPE: protein     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:     MetGluIleGluLeuSerThrCysPhePheLeuCysLeuLeuArgPhe     151015     CysPheSerAlaThrArgArgTyrTyrLeuGlyAlaValGluLeuSer     202530     TrpAspTyrMetGlnSerAspLeuGlyGluLeuProValAspAlaArg     354045     PheProProArgValProLysSerPheProPheAsnThrSerValVal     505560     TyrLysLysThrLeuPheValGluPheThrAspHisLeuPheAsnIle     65707580     AlaLysProArgProProTrpMetGlyLeuLeuGlyProThrIleGln     859095     AlaGluValTyrAspThrValValIleThrLeuLysAsnMetAlaSer     100105110     HisProValSerLeuHisAlaValGlyValSerTyrTrpLysAlaSer     115120125     GluGlyAlaGluTyrAspAspGlnThrSerGlnArgGluLysGluAsp     130135140     AspLysValPheProGlyGlySerHisThrTyrValTrpGlnValLeu     145150155160     LysGluAsnGlyProMetAlaSerAspProLeuCysLeuThrTyrSer     165170175     TyrLeuSerHisValAspLeuValLysAspLeuAsnSerGlyLeuIle     180185190     GlyAlaLeuLeuValCysArgGluGlySerLeuAlaLysGluLysThr     195200205     GlnThrLeuHisLysPheIleLeuLeuPheAlaValPheAspGluGly     210215220     LysSerTrpHisSerGluThrLysAsnSerLeuMetGlnAspArgAsp     225230235240     AlaAlaSerAlaArgAlaTrpProLysMetHisThrValAsnGlyTyr     245250255     ValAsnArgSerLeuProGlyLeuIleGlyCysHisArgLysSerVal     260265270     TyrTrpHisValIleGlyMetGlyThrThrProGluValHisSerIle     275280285     PheLeuGluGlyHisThrPheLeuValArgAsnHisArgGlnAlaSer     290295300     LeuGluIleSerProIleThrPheLeuThrAlaGlnThrLeuLeuMet     305310315320     AspLeuGlyGlnPheLeuLeuPheCysHisIleSerSerHisGlnHis     325330335     AspGlyMetGluAlaTyrValLysValAspSerCysProGluGluPro     340345350     GlnLeuArgMetLysAsnAsnGluGluAlaGluAspTyrAspAspAsp     355360365     LeuThrAspSerGluMetAspValValArgPheAspAspAspAsnSer     370375380     ProSerPheIleGlnIleArgSerValAlaLysLysHisProLysThr     385390395400     TrpValHisTyrIleAlaAlaGluGluGluAspTrpAspTyrAlaPro     405410415     LeuValLeuAlaProAspAspArgSerTyrLysSerGlnTyrLeuAsn     420425430     AsnGlyProGlnArgIleGlyArgLysTyrLysLysValArgPheMet     435440445     AlaTyrThrAspGluThrPheLysThrArgGluAlaIleGlnHisGlu     450455460     SerGlyIleLeuGlyProLeuLeuTyrGlyGluValGlyAspThrLeu     465470475480     LeuIleIlePheLysAsnGlnAlaSerArgProTyrAsnIleTyrPro     485490495     HisGlyIleThrAspValArgProLeuTyrSerArgArgLeuProLys     500505510     GlyValLysHisLeuLysAspPheProIleLeuProGlyGluIlePhe     515520525     LysTyrLysTrpThrValThrValGluAspGlyProThrLysSerAsp     530535540     ProArgCysLeuThrArgTyrTyrSerSerPheValAsnMetGluArg     545550555560     AspLeuAlaSerGlyLeuIleGlyProLeuLeuIleCysTyrLysGlu     565570575     SerValAspGlnArgGlyAsnGlnIleMetSerAspLysArgAsnVal     580585590     IleLeuPheSerValPheAspGluAsnArgSerTrpTyrLeuThrGlu     595600605     AsnIleGlnArgPheLeuProAsnProAlaGlyValGlnLeuGluAsp     610615620     ProGluPheGlnAlaSerAsnIleMetHisSerIleAsnGlyTyrVal     625630635640     PheAspSerLeuGlnLeuSerValCysLeuHisGluValAlaTyrTrp     645650655     TyrIleLeuSerIleGlyAlaGlnThrAspPheLeuSerValPhePhe     660665670     SerGlyTyrThrPheLysHisLysMetValTyrGluAspThrLeuThr     675680685     LeuPheProPheSerGlyGluThrValPheMetSerMetGluAsnPro     690695700     GlyLeuTrpIleLeuGlyCysHisAsnSerAspPheArgAsnArgGly     705710715720     MetThrAlaLeuLeuLysValSerSerCysIleProGluGlyGluGlu     725730735     AspAspAspTyrLeuAspLeuGluLysIlePheSerGluAspAspAsp     740745750     TyrIleAspIleValAspSerLeuIleGluProArgSerPheSerGln     755760765     AsnSerArgHisProSerThrArgGlnLysGlnPheAsnAlaThrThr     770775780     IleProGluAsnAspIleGluLysThrAspProTrpPheAlaHisArg     785790795800     ThrProMetProLysIleGlnAsnValSerSerSerAspLeuLeuMet     805810815     LeuLeuArgGlnSerProThrProHisGlyLeuSerLeuSerAspLeu     820825830     GlnGluAlaLysTyrGluThrPheSerAspAspProSerProGlyAla     835840845     IleAspSerAsnAsnSerLeuSerGluMetThrHisPheArgProGln     850855860     LeuHisHisSerGlyAspMetValPheThrProGluSerGlyLeuGln     865870875880     LeuArgLeuAsnGluLysLeuGlyThrThrAlaAspProLeuAlaTrp     885890895     AspAsnHisTyrGlyThrGlnIleProLysGluGluTrpLysSerGln     900905910     GluLysSerProGluLysThrAlaPheLysLysLysAspThrIleLeu     915920925     SerLeuAsnAlaCysGluSerAsnHisAlaIleAlaAlaIleAsnGlu     930935940     GlyGlnAsnLysProGluIleGluValThrTrpAlaLysGlnGlyArg     945950955960     ThrGluArgLeuCysSerGlnAsnProProValLeuLysArgHisGln     965970975     ArgGluIleThrArgThrThrLeuGlnSerAspGlnGluGluIleAsp     980985990     TyrAspAspThrIleSerValGluMetLysLysGluAspPheAspIle     99510001005     TyrAspGluAspGluAsnGlnSerProArgSerPheGlnLysLysThr     101010151020     ArgHisTyrPheIleAlaAlaValGluArgLeuTrpAspTyrGlyMet     1025103010351040     SerSerSerProHisValLeuArgAsnArgAlaGlnSerGlySerVal     104510501055     ProGlnPheLysLysValValPheGlnGluPheThrAspGlySerPhe     106010651070     ThrGlnProLeuTyrArgGlyGluLeuAsnGluHisLeuGlyLeuLeu     107510801085     GlyProTyrIleArgAlaGluValGluAspAsnIleMetValThrPhe     109010951100     ArgAsnGlnAlaSerArgProTyrSerPheTyrSerSerLeuIleSer     1105111011151120     TyrGluGluAspGlnArgGlnGlyAlaGluProArgLysAsnPheVal     112511301135     LysProAsnGluThrLysThrTyrPheTrpLysValGlnHisHisMet     114011451150     AlaProThrLysAspGluPheAspCysLysAlaTrpAlaTyrPheSer     115511601165     AspValAspLeuGluLysAspValHisSerGlyLeuIleGlyProLeu     117011751180     LeuValCysHisThrAsnThrLeuAsnProAlaHisGlyArgGlnVal     1185119011951200     ThrValGlnGluPheAlaLeuPhePheThrIlePheAspGluThrLys     120512101215     SerTrpTyrPheThrGluAsnMetGluArgAsnCysArgAlaProCys     122012251230     AsnIleGlnMetGluAspProThrPheLysGluAsnTyrArgPheHis     123512401245     AlaIleAsnGlyTyrIleMetAspThrLeuProGlyLeuValMetAla     125012551260     GlnAspGlnArgIleArgTrpTyrLeuLeuSerMetGlySerAsnGlu     1265127012751280     AsnIleHisSerIleHisPheSerGlyHisValPheThrValArgLys     128512901295     LysGluGluTyrLysMetAlaLeuTyrAsnLeuTyrProGlyValPhe     130013051310     GluThrValGluMetLeuProSerLysAlaGlyIleTrpArgValGlu     131513201325     CysLeuIleGlyGluHisLeuHisAlaGlyMetSerThrLeuPheLeu     133013351340     ValTyrSerAsnLysCysGlnThrProLeuGlyMetAlaSerGlyHis     1345135013551360     IleArgAspPheGlnIleThrAlaSerGlyGlnTyrGlyGlnTrpAla     136513701375     ProLysLeuAlaArgLeuHisTyrSerGlySerIleAsnAlaTrpSer     138013851390     ThrLysGluProPheSerTrpIleLysValAspLeuLeuAlaProMet     139514001405     IleIleHisGlyIleLysThrGlnGlyAlaArgGlnLysPheSerSer     141014151420     LeuTyrIleSerGlnPheIleIleMetTyrSerLeuAspGlyLysLys     1425143014351440     TrpGlnThrTyrArgGlyAsnSerThrGlyThrLeuMetValPhePhe     144514501455     GlyAsnValAspSerSerGlyIleLysHisAsnIlePheAsnProPro     146014651470     IleIleAlaArgTyrIleArgLeuHisProThrHisTyrSerIleArg     147514801485     SerThrLeuArgMetGluLeuMetGlyCysAspLeuAsnSerCysSer     149014951500     MetProLeuGlyMetGluSerLysAlaIleSerAspAlaGlnIleThr     1505151015151520     AlaSerSerTyrPheThrAsnMetPheAlaThrTrpSerProSerLys     152515301535     AlaArgLeuHisLeuGlnGlyArgSerAsnAlaTrpArgProGlnVal     154015451550     AsnAsnProLysGluTrpLeuGlnValAspPheGlnLysThrMetLys     155515601565     ValThrGlyValThrThrGlnGlyValLysSerLeuLeuThrSerMet     157015751580     TyrValLysGluPheLeuIleSerSerSerGlnAspGlyHisGlnTrp     1585159015951600     ThrLeuPhePheGlnAsnGlyLysValLysValPheGlnGlyAsnGln     160516101615     AspSerPheThrProValValAsnSerLeuAspProProLeuLeuThr     162016251630     ArgTyrLeuArgIleHisProGlnSerTrpValHisGlnIleAlaLeu     163516401645     ArgMetGluValLeuGlyCysGluAlaGlnAspLeuTyr     165016551660     (2) INFORMATION FOR SEQ ID NO:3:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 48 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:     TCGACCTCCAGTTGAACATTTGTAGCAAGCCACCATGGAAATAGAGCT48     (2) INFORMATION FOR SEQ ID NO:4:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 40 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:     CTATTTCCATGGTGGCTTGCTACAAATGTTCAACTGGAGG40     (2) INFORMATION FOR SEQ ID NO:5:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 30 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:     GGGTCGACCTGCAGGCATGCCTCGAGCCGC30     (2) INFORMATION FOR SEQ ID NO:6:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 38 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:     GGCCGCGGCTCGAGGCATGCCTGCAGGTCGACCCTGCA38     (2) INFORMATION FOR SEQ ID NO:7:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 36 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:     CTGAAGGTTTCTAGTTGTATTCCAGAGGGGGAGGAG36     (2) INFORMATION FOR SEQ ID NO:8:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 39 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:     GGAGAAGCTTCTTGGTTCAATCAGACTGTCGACGATGTC39     (2) INFORMATION FOR SEQ ID NO:9:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 21 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:     TCTAGCTTCAGGACTCATTGG21     (2) INFORMATION FOR SEQ ID NO:10:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 20 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:     ATACAACTAGAAACCTTCAG20     (2) INFORMATION FOR SEQ ID NO:11:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 21 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:     GTAGATCAAAGAGGAAACCAG21     (2) INFORMATION FOR SEQ ID NO:12:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 19 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:     GTCCCCACTGTGATGGAGC19     (2) INFORMATION FOR SEQ ID NO:13:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 44 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:     AGGAAATTCCAGAGGAATATTTGCAGAGTAAAAACAATGCCATT44     (2) INFORMATION FOR SEQ ID NO:14:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 43 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:     AATATTCCTCTGGAATTTCCTCGAAATCACCAGTGTTCTTGTC43     (2) INFORMATION FOR SEQ ID NO:15:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 38 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:     ValSerSerCysAspLysAsnThrGlyAspTyrTyrGluAspSerTyr     151015     GluAspIleSerAlaTyrLeuLeuSerLysAsnAsnAlaIleGluPro     202530     ArgSerPheSerGlnAsn     35     (2) INFORMATION FOR SEQ ID NO:16:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 43 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:     ValSerSerCysIleProGluGlyGluGluAspAspAspTyrLeuAsp     151015     LeuGluLysIlePheSerGluAspAspAspTyrIleAspIleValAsp     202530     SerLeuIleGluProArgSerPheSerGlnAsn     3540     (2) INFORMATION FOR SEQ ID NO:17:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 34 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:     ValSerSerCysAspLysAsnThrGlyAspPheGluGluIleProGlu     151015     GluTyrLeuGlnSerLysAsnAsnAlaIleGluProArgSerPheSer     202530     GlnAsn     __________________________________________________________________________ 

What is claimed is:
 1. A method of modifying a blood coagulation protein, comprisingreplacing at least one acidic region of a Factor VIII protein with an acidic region from hirudin or heparin cofactor II.
 2. A method of modifying a blood coagulation protein,replacing at least one acidic region of a Factor VIII mutant lacking part of the B-domain with an acidic region from hirudin or heparin cofactor II. 